How it works : Science experiments

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Rubbing the pen 6 Hold a plastic pen near SCIENCE IN SECONDS Bending water
gives it a static the tinfoil ball. Nothing Charge a plastic comb by running it
happens. Now rub the pen through dry hair several times. Turn on
charge as it hard on a cloth and try again. a tap so that a narrow stream of water
strips electrons The foil leaves inside the jar ly is lowing. Bring the teeth of the
from the cloth apart, indicating a static charge. charged comb up to the water. You will
see the water bend towards the comb.
Water molecules have a positive end
and a negative end. The negatively
charged comb attracts the positive
ends of the water molecules.

Tape the lid EUREKA MOMENTS
on to create a
tight seal

Amber
The words “electricity” and “electron”
both come from the Greek word for
amber: elektron. Amber – fossilized tree
resin – is a bright orange substance
often used in jewellery. The ancient
Greeks knew that when they rubbed a
piece of amber with a cloth, the amber
attracted bits of ash and dirt.
They didn’t know it, but
they had discovered
static electricity.

SCIENCE AROUND US 101

Electric touch
Static charges are responsible for
the tiny shocks you sometimes get
when you touch a metal door handle.
They also make your hair stand on
end when you pull a woollen jumper
over your head or rub your hair with
a balloon. The strands of hair are
attracted to the charged item and are
so light they are lifted up towards it.

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fasfhLiAosnhalight YOU WILL NEED:
Acswatnaolletreiklcde–ceetlllireegiccchtttcrriinoucgnrirtsyeth,ntehatanibstueaallbersecottrfmreaicaotmvcoinurocgrfrhein,nnfeottghrcaeeatixnsvaaeemmlyapescliehldy.airbregecetudiospnea.drUttinoclliekdseo
Small plastic bottle
1 Cut the neck off a small Scissors
plastic bottle. This will be the Empty cardboard sweets tube
relector of your torch. Line Aluminium foil
the inside of it with aluminium Two 1.5-volt C (R14) batteries
foil, ixing the foil in position Two 15-cm (6-in) lengths of insulated
with glue or clear sticky tape. wire, all four ends stripped to
approximately 1 cm (0.4 in)
3-volt torch bulb
Modelling clay
Paper clip
Two brass fasteners
Electrical tape
Paper and glue to decorate

30 mins

electric currents 2 Take the top off your 6 Wrap the end of the second
empty sweets tube. This wire around the bottom of
will be the body of your the bulb and secure it with
torch. If you want to decorate electrical tape. Hold the bulb
it, use glue and coloured paper against the top of the battery in
to cover it, then leave it to dry. the tube and use modelling clay
to secure it tightly in place.
3 Make two small, vertical slits
in the tube, about the length
of a paper clip apart. Ask an
adult to strip the ends of your wires.
Thread a piece of wire through each
slit. Wrap the exposed end of one
wire around a brass fastener and
press the fastener through the slit.

4 Repeat with the second piece
of wire and another fastener, but
this time slip a paper clip onto
the fastener before attaching the wire.
Inside the tube, bend back the legs of
the fasteners so that they are lush with
the side of the tube, but make sure
that they are not touching.

5 Tape the two batteries 7 Push the relector into the
together, making sure that the tube, narrow end irst, so that
positive and negative terminals it is secured in place by the
are touching. Tape the end of one modelling clay. To switch the torch
wire to the bottom battery, then push on, touch the paper clip against the
both batteries fully into the tube. second brass fastener, completing
the circuit and lighting up the bulb.
102

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how does SCIENCE IN SECONDS Testing for conductors
this work? Materials that conduct electricity are
called conductors; those that do not
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different directions do material is a conductor, hook up a
not produce a current simple circuit. Connect the object you
want to test to a battery and a small
light bulb. If the object is a conductor,
the bulb will light up.

Other particles in Electrons lowing in
the conductor the same direction
do not move produce a current

Electricity will only
flow if it has a complete

circuit to go around, so
the bulb lights up only

when the paper clip
connects the fasteners

TOP TIP 103

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Lighten up! YOU WILL NEED:
IuGinfsveyientotnguinteogmlreisatcntttooaroigcwkeaomlirtrkoietrissweisnittlohlabatnrnacigse1h0ett0aoesynmyeyaaaorskuseirttodaloapotyehk.risnf!eTccohtiitlshoiesf iawnctirraiecn,kdoyersefcxilepanemtrielmigneht,ntgtb,luoblwbut,.
Jar with lid
Paper clip
Nail
Thick insulated electrical wire, at least

2.5 mm (0.1 inch) diameter
Crocodile clips
Tea light candle
Heavy duty 6-volt lantern battery
Glue
Wire cutters
Wire strippers

20 mins

Electrical Resistance 1 Cut two pieces of thick wire 2 Get an adult to drill two
about 30 cm (12 in) in length. holes in the top of the jar’s
At one end of each attach a lid, just big enough for your
crocodile clip. Ask an adult to wire to it through. Push the wires
strip off about 2 cm (0.8 in) of the through the holes, hooked ends
insulation from the other ends irst, and glue them in place.
and bend the wire into a hook.

3 Straighten out a paper clip
and then curl it around a
nail to make a coil. This
can be quite tricky, so ask an
adult to help you. Rest the coiled
paper clip in the hooks of wire.
This is your ilament.

4 Light a tealight and TOP TIP
drop it into the jar. Put
the lid on tightly. After a twhAytbriroeraoyfeuaitulustaamgeismlrhyriaenye,cygbuntobhustameaitmntnpihgmtalisemndaaptnedeilegeeelocyhsriu.ttsffoHitiealpaoogldosmfwlowohteewehebnvirrunteemfr.u,rinro,loirfne
few seconds the candle will run
out of oxygen and go out.

104

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EUREKA MOMENTS

how does Switching on the lights
this work? US inventor Thomas Edison (1847–1931) was one of many
scientists who made the irst light bulbs. His 1879 bulb had a
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and make it burn out more quickly. have a tungsten ilament that heats up to about 3,000°C (5,500°F)
and are illed with an inert (non-reactive) gas so that the ilament
does not burn through.

5 Turn out the lights Energy-saving light bulbs SCIENCE AROUND US
and attach your metal Incandescent bulbs glow by producing a large amount of
clips to the terminals heat, making them very ineficient. Increasingly, they are
of the battery. After a few being replaced with bulbs that work in a different way.
seconds the paper clip Fluorescent energy-saving bulbs produce light without
should begin to glow. producing much heat. They use electricity to energize
mercury vapour. This produces invisible ultraviolet rays.
WARNING! A chemical coating inside the bulb changes the UV light
into visible light.
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105

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Salty circuit YOU WILL NEED:
EcAInloedntcdhttianirsoignclysiirtaocelntusstitoa(yewroleeauct’mltelrrsiicxe(aateulwlrytehecsaahtktaaherdagledtecidntcrgoposnalyadrttlueticc)bltteousore)nsltesthsciattttrihniceatiortbeyarifsgwrthereteonllnetgobseesmrcoeaofluveaescebtaruobtlblhoy.euteyt..
Glass dish
1 Take two wires, each with 2 Connect one wire to one Water
a crocodile clip on one end terminal of the battery and Salt
only. Put the free end of the the other wire to the light bulb. 9-volt battery
wires into a glass dish and tape Use a third wire to connect the Small bulb
them in position on opposite sides. bulb to the other terminal Three lengths of electrical wire,
Now ill the dish with water. of the battery.
insulation stripped from the ends
Electrolytes Crocodile clips
Table salt
EUREKA MOMENTS Plastic spoon

15 mins

WARNING!

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3Slowly add table salt to
the water, stirring it with
a plastic spoon (which does
not conduct electricity) to help the
salt dissolve. The more salt you add,
the more brightly the bulb glows.

Cardboard Copp er
soaked in disc
saltwater
Zinc
disc

Bright sparks how does
The irst practical battery was built in 1800 by this work?
Italian physicist Alessandro Volta (1745–1827).
In his “voltaic pile”, discs of zinc and copper were Uintrotohehusfnraeumodssaueibocflgfllenaeyehr,ncrt.eaohtcrInnfanoattisneromitrsldnhyeeestecahttattlerhehclinscemue.rmcwlorAeuenoamnrcsvtrtheeoe.pernnArtmtc,oodoiidwiosdcnuniaactncsarlagdeirrcnesrmaosiaetm,occhdmtruepieborelsreynaeaitlnnneevsdtieltnetrrihmigcspcettosarohocriesaeninrltt,csersotp,ucahbnirtlteortguoidtncetnouorisancwicnfisaunrasionrgmtreimneeairlnlatteictnhhrcucceewtrramrrecoaneaoylnay.psptrtTea.eepshsemserthacedoein;
separated by pieces of cardboard soaked in salty
water. It worked in the same way as your lemon
battery to produce an electric current. The unit for
electrical force, the volt, is named after him.

106

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See a citrus YOU WILL NEED:
Current
Three lemons
A battery uses an electrolyte to produce an electric Sharp knife
current from a chemical reaction. But you don’t need Copper and silver coins
batteries – some lemons will do! Lemon juice is an Three lengths of electrical wire,
acid that can provide enough power to light up an LED.
insulation stripped from the ends
Crocodile clips
Voltmeter

15 mins

1 One by one, roll your 2 Ask an adult to make two 3 Push a copper coin and 4 Use crocodile clips and
lemons on a table to slits in the skin of each a silver coin into the slits two wires to connect
release the juices inside lemon using a sharp knife. you made in each lemon. the three lemons. Each
them. This will help the The slits should be the same Make sure that the coins are wire should run between a
current to low. width as your coins. touching the fruits’ lesh. silver coin and a copper coin.

TOP TIP 5 Connect the last copper
coin and the last silver coin
tochZtoehiTmnesrcripylvncaoeDiarttreiorh-luscewaasowrpbiftlfpooorhruluurueykirtitstoespwaudwotnreotcodllaleorstkivmienon?eeesopgW.snlheaH?ohtcboawaeaobttkolttehefuserp.yy. to a voltmeter. Three lemons
can produce up to about 3 volts –
enough to light up an LED.

Electrons flow
from the copper
coin to the
silver coin

107

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tune in to a YOU WILL NEED:
homemade radio
25-m (82-ft) insulated single-core wire
Rwwtbhaaaaedtvvmiteoeelsreiwuenapsgnatdv–hoe.ttnsrhSaeovaaureranelhddlooiaomnwgweatymvdapeivsaesetdasceontafchnreeaesbmdneiaseoremr,oglvuayaendnsdedwptatrhoyvoeoevhuigidtwlceodhbiottehhna.e’tYracidoeueuvvrerecoernanynntr.nlapoedinceigokd Three lengths of electrical wire
Crocodile clips
Cardboard tube
Pencil
Crystal earpiece
Germanium diode
Copper wire
10-m (34-ft) wire for aerial

1 hour

Radio signals how does 1 Make two holes about 1 cm
this work? (0.4 in) apart at the top and
bottom of a cardboard tube.
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stays the same, but its size varies. wire through the top two holes and
pull about 4 cm (1.5 in) through.
This anchors the wire in place.

2 Wind the wire around the
cardboard tube, keeping
the coils close together.
After six turns, place a pencil
down the side of the tube and
wrap the wire around the
pencil to make a small loop.
Continue like this, with six
turns then a loop, until you
reach the bottom of the tube.

Carrier wave has a Sound wave changes the
certain frequency amplitude of the carrier wave

EftTfigrwrueaehletralcqeenravmhurst,ceienraoutanshgnrndocreileutyiyootenm.hantTtsalheldphttoaereiatgwothssiaydoiseoneenetugerhsirnhaaaeadatrltchpssotewrihifoeigitvaeyucsnevyoegaseouchlcwtrfoohartnrnofhneatmoecdaccnaciiuonoterohrnrriiifpevnelerieeotrncboqrftwkittuwstaaiiretnneivunrbydleepaca,estywcriwleanekitptdhghchiaiirtnoctorraotihauocwpttgaechsaahcsouevr.tterutsicTrhcsneahleudinarkelr.tbaneiserdi.tar 3 Thread the wire through
the two holes at the
bottom of the tube as
you did at the top. Leave
15 cm (6 in) then cut the wire.
Slide the pencil out and ask
an adult to strip the insulation
from the end of the wire
and from each of the loops.

108

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WARNING! 5 Connect the base of 6 Your radio needs an earth
your aerial to the loop connection. Twist a copper
oYrtiumhoipteuopwrryvoeoreirlatliursadhnrnaeiooatnatentydwrheidapaoealotrdaknwysn.goeHayeurworldlowiohnonfeeegnlrvsiegaoeohetrnrt,rpeniiiatufainltirsg. at the top of your wire into a coil. Connect it to
radio using a length of wire the wire at the bottom of your radio
4 Ask an adult to run at least 10 m (33 ft) and two crocodile clips. using a wire and two crocodile clips,
of wire from somewhere high up, such then bury the coil in the ground.
as a tree, to the place where you want Connect earpiece
to listen to your radio. This is your aerial. to diode with TOP TIP
wire and two
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This wire connects to Clip this
the earth wire connection
to a loop on
7 Ask an adult to strip the insulation off the ends of the radio
the crystal earpiece’s wires. Connect one of them
to the germanium diode, then connect the other
side of the diode to one of the loops on your radio.
Connect the other side of the earpiece to the wire at the
bottom of the radio (the one the earth wire connects to).

8 Put the earpiece in and see if Aerial introduces
you can hear anything. If not, try a current into
moving the metal clip connected the radio
to the diode to a different loop on the
coil and listen again.

Earpiece converts Germanium diode
electrical current receives the
into sound current and
separates the
information
it carries

Earth connection
gives the current

somewhere to
flow to, so your
radio works better

109

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WorldMags.net

Make a metal YOU WILL NEED:
detector
MdgMereaottkeuaecnl tdoyo,obrb.ujoerTucohtnwiscsenhdioadefndvfdiecmnseeeutueanswldeoeshbrajientthvcyeitossui,gbarcleonaudnrnaafddirnieocdta!hwneanbvepeiscfoktuhenaddtuppbaybsyusstthinhegrodauegtmehcettthoaerl. Empty CD case
Double-sided tape
AM radio
Battery-powered calculator

10 mins

ELECTROMAGNETISM Mine detectors 1 Take an empty CD case and TOP TIP
SCIENCE AROUND US During wars, mines (explosive devices) and stick the calculator to one side
IEDs (improvised explosive devices) are often of it using double-sided tape. ctisuhsAoraMnaccnIkatrfgbhaenyeaedtosns,iouvtodirnor,syyltrttuouauhamundsetieiiehonoteongiuthanpaeaaretasstoobrtacnphoenllheoythtoseeesinegantrehra,daps.btshiIoucftoyfot.tonthdhhueeoeernae’rt
buried under ground that enemy troops might Turn the calculator on.
cross. Hidden just beneath the surface, the
devices detonate when disturbed and pose a
great danger to both military personnel and
civilians. One method for inding them so that
they can be cleared uses metal detectors. The
detectors are moved from side to side across
the ground, searching for metal parts.

2 Stick the radio to the other
side of the CD case with
double-sided tape. Both
the radio and the calculator
should be facing inwards.

SCIENCE AROUND US

Treasure hunting 3 Turn the radio on and tune it to the
Metal detecting is a popular hobby across top of the AM (medium wave) band,
the world. Some people look for valuable making sure not to tune it to a station.
metals in their natural form of nuggets or Turn up the volume so that all you can hear
lakes (prospecting), others search beaches is static (hissing). Close the CD case until
(beach combing) and other areas likely to you can hear a loud tone.
yield buried metal. Occasionally, metal
detectorists unearth hoards of coins and
other ancient relics buried or lost centuries
ago. In 2010, an enthusiast found a pot
containing more than 50,000 3rd-century
Roman coins in a ield in Somerset, England.

110

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how does Radio waves are Radio waves given
this work? relected from out by the calculator
the metal key
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materials but not metals.

4 Open the case again until you can The CD case holds
only just hear the tone. Hold the the calculator and
case in this position. When you
move the detector over something made radio in pla ce
of metal, the tone will grow louder.

The radio emits a 111
tone when metal

is nearby

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micrmoestceoopricites YOU WILL NEED:

Matphteemrrtoseoueosgvrphietherteahsrneecasaerkneyadnacfdhnaudlalenosnktnsrtloyonoftgfahleelstnpgooaroutchugeenhdrgmo.rSocaokugmnntdeehtwa,atyhroeehunsaocvitaetrninaeyfininntsthd.eaWrotenidttehh.eEayabrflitothao’stf Shallow tray
Paper cup
String
Strong magnet
Microscope or magnifying glass
A rainy day

20 mins

MAgnetism 1 When rain is forecast, place a 2 Bring the tray inside and put it
shallow tray outside somewhere that in a warm place. Leave it until
it won’t be disturbed. Your tray must all the water has evaporated.
be thoroughly clean beforehand. Micrometeorites are not visible to the
Leave it to collect rainwater. naked eye, but there may be specks
of dust or dirt left on the tray.

3 Take your paper cup and
make two holes opposite
each other near the rim.
Thread a length of string through
them to make a handle and place
a magnet inside the cup.

TOP TIP 4 Sweep the cup over the tray. 5 Tap your cup onto the slide of a
Any magnetic metallic dust will microscope. If you don’t have
aTBrhvomaeetrrahesygtoenrsofaotebrrtntohttsghaneeaigsemnsreaateparbamegtalchrenamctemgithvtaynesianpte.aigeeetNpnsnsoeetaarfotnmer.dredqayaurcemgeiaranieluseleimtldy. be attracted by the magnet a microscope, tap the cup over a
and stick to the bottom of the cup. sheet of white paper and use a magnifying
Some of these pieces may be glass. What can you see? Any particles
micrometeorites, attracted to the that are spherical or look like lakes could
magnet because they contain iron. have come from outer space.

112

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WorldMags.net

magnetic YOU WILL NEED:
breakfast
Breakfast cereal
It might not sound very appetizing, but iron is vital for a Blender
healthy diet. Using its magnetic properties, you can Plastic storage bag
separate this metal from your breakfast cereal. Strong magnet
Hot water

20 mins

1 Put a cup of cereal into a how does
blender and add some this work?
hot water – just enough
to cover all of the cereal. All magnets are surrounded by a field that is strongest at its ends,
Turn on the blender for or poles. When two magnets are near each other, their opposite
about 1 minute, until your poles attract and like poles repel. Anything that attracts iron is
cereal mixture is thoroughly classed as a magnet. Materials that behave like magnets when
blended with no lumps. inside a magnetic field are known as magnetic materials.

Lines of force are NS
concentrated near

the poles

2 Pour the blended mixture The atoms in magnetic materials are arranged in groups, or
into a plastic storage bag domains, which act like tiny magnets. Normally, the domains point
and zip the bag shut. in all directions, cancelling out their magnetism. In a magnetic
Leave it to sit for 5 minutes – field, the domains line up, making the material magnetic. Some
this will allow the iron to sink materials, such as nickel and iron, lose their magnetic field when
to the bottom. they are removed from the field. Others, such as steel, become
permanent magnets if magnetized once.
3 Take your magnet and run it
along the bottom of the bag, Unmagnetized Magnetized
using lots of even strokes in the domains domains
same direction. The little black specks
that you will see collecting around the
magnet are pieces of iron.

SCIENCE AROUND US 113

Iron in you
Our bodies need iron to function, which
is why tiny amounts of it are sprayed
onto the surface of breakfast cereals.
On average there is 4 g (0.14 oz) of iron
in a human body. Most of it is used in
a substance called haemoglobin, a
protein found inside red blood cells.
Haemoglobin carries oxygen from
the lungs around the body.

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WorldMags.net

BEULIELCDTARNOMAGNET YOU WILL NEED:
Emwlfolreahuocgedmtnrsreepoatemssaaiatmkhgmepenralyesegtcnassacennartdeirbcewdeifdsseiecrwlielvdidctecrtriirhv.siceeadsol.nloyYlnyopaunonewdceaeodnrfefe,dmdmasamkokeamingygenoetuhotrsef.motUwhunenslieketfielumelcepftoe,rrrosmdmueacavnhgiceneanesstt
Screwdriver with a plastic handle
Insulated wire
4.5-volt battery
Sticky tape
Ruler
Steel paper clips
Wire strippers or scissors

30 mins

ELECTROMAGNETISM TOP TIP

ayfTofeurDycr8otves0ealestrchocyoaentininrleosmgemwwatlehagiotcegnhrtknenrjoetuubimtscmetttafbot4igeee0snlrrde?etoepthfrawhconooidtwihulscteohdnis.

1 About 30 cm (12 in) from 2 Wrap the wire tightly
one end of your wire, stick around the metal blade of
the wire to the base of the the screwdriver 60 times.
screwdriver’s handle, where Use sticky tape around the last
it meets the blade, with a turn to hold it securely in place.
piece of tape.

SCIENCE AROUND US 3 Leave a length of 30 cm (12 in)
then cut the wire. Ask an adult to
No wheels necessary remove the insulation from the last
Electromagnets provide the power for futuristic levitating trains 2–3 cm (1 in). Then strip the same amount
called maglevs. The world’s irst commercial high-speed maglev off the end attached to the handle.
carries passengers between Shanghai and its international airport at up
to 431 kph (268 mph). The sides of the train wrap underneath the track.
Electromagnets at the bottom of these sides and in the track above them
attract each other, lifting the train so that it hovers above the track.

4 Connect one end of the
wire to one terminal of the
battery, and the other end
to the battery’s other terminal.

114

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WorldMags.net

how does EUREKA MOMENTS Compass clue
this work? The irst person to notice that electric
currents produce magnetism was
Eeiwlsillkeeoteccuuttrtnrrhnidiccaeiitdittnyyotoofflafafona,wdbtchsamoe,rialimmtgppaanrorggeodnntdiueesucttmci,eseasmasnradeadmivumsesoaarirpnygepgncceelaooatnrsmicsec.elfieyAtenarltlcedrcaul.aotrWterreeedhdnemm.t-nWcaatakghherneerseyncittnihucgerrfiweenilrdte, Danish scientist Hans Christian
magnetism even stronger. Oersted (1777–1851). In 1820, he
noticed a compass needle twitch
Magnetic ield when an electric current was switched
on nearby. In 1931, English scientist
Michael Faraday (1791–1867) showed
that the relationship also works in
reverse. He pushed a magnet into a
coil of wire and found that a moving
magnet created a current.

North South
pole pole

Direction of current

If the current were lowing in
the opposite direction, the
poles would switch places

5 Touch the end of Screwdriver
the screwdriver blade becomes a magnet
to some paper clips. when the current
How many can it pick up? is switched on
Disconnect the wires
from the battery and try TOP TIP
again – the screwdriver
should lose its magnetism. scetasxisclnmpciSkgeriochtetrrrtioiwpnmeelyittcwdseohmkrtndeiiavcautrmneikgpv—r.ne?etShieolrsTeoestcibhiwetcsteeaorhtnfmofmiooptmtarweeeesnratsomyigsttmutntpahahreeagonrastptnwi.tniehnegsargmtciivcctrtaeelhinypweaoyssur

115

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make a motor YOU WILL NEED:

Eruwmelsepauecsucdthlhrsiiinicnopgnoamwlmtl ooesatroccorbohrtussnintveoeiutsfrs.twmeTeoahlreeckislhcesitcnrsotieicnrmsoitepmyfxlreaoiangmctvntoeleyhrmtisgitcihoohev-naessptmwatermeoeanncdet’tt.pitorTrpanihnrionecavsyipin’drtldeeoe. D-cell battery (1.5 volts)
Get spinning! Strong magnet
1 m (3 ft) of enamelled copper wire,
At one end of also called magnet wire
the wire, remove AA battery, marker pen, or item of
only half of similar width
the insulation Rubber bands
Two large paper clips

30 mins

ELECTROMAGNETISM 1 Make a coil by wrapping 2 Ask an adult to scrape the 3 Bend the paper clips in the
enamelled copper wire enamel coating off one end middle to form supports for
20 times around an AA battery of the wire using scissors the coil. Place one paper clip
or chunky marker pen. Leave or sandpaper. Then scrape the on each end of the D-cell battery
about 5 cm (2 in) of wire sticking enamel off the other end of the and wrap rubber bands around the
out from each side of the coil. wire – but this time only remove battery to hold the clips in position.
Slide the coil off the pen and it from one side. Leave the other
wrap the ends around the inside side in tact.
of the coil to stop it unwinding.

how does Permanent magnet
this work? alternately attracts and
repels the rotor to make it
Aepnhtpttstachltsunoheaheeihtueomraellectreeefnrrmrtrrtplascabrroewehiooclaunycatenetittmnorurtrotetprevrecer,hreradi’een,ocnslentaegrr.uatittmstlmmansoTnrtmliivaenriosahdaoktaimtsanhnnegteacwgcogeetnettwchtanrtenhehmuirdleeodnctealtireisitrosanmcrcrctkdeeuagnotmustapencnltnharaagtdtaotrideehtnieirnkoliinteoesioncc.eneansstntouItsto.on,ah,samorpCortssirme.fmhseprntopfonIoeeeantolenihsetrialrktstavaciteatdeiinirreietonntvlsusifoerswngoiuenlyorrogfrapeaaststsffhhlrhpopynleetoyap.eoliheadvennluTrfltrnec,s.leeholhetsdrorYvueueosdeeeioerrsglifvnsncnrbuorhhea.dsgoo,ryuariitisnottltlatfh,ihghifntsieeetgaBisnatetelercytsriucptchpuelircercoeCsunmorrtrmemevnpuetonrsenicmivenaenagtrotgytrcnhhaereealtlvilercfoedttriuosterhernl’dess,
spin continuously

n

s

Rotor turns into a
magnet when the electric
current is switched on
Electric motor

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WorldMags.net

Michael’s motor EUREKA MOMENTS Motor in minutes SCIENCE IN SECONDS
The very irst electric motor was invented This simple motor has even fewer
by English scientist Michael Faraday Wire moves components but demonstrates a
(1791–1867) in 1821. He hung a wire so around the similar principle. Strip about 12 mm
that the end dipped into a dish of mercury – magnet (0.5 in) of insulation from each end of
a metal that is liquid at room temperature. a 15 cm (6 in) piece of wire. Snap a
The wire was free to move. A magnet sat in neodymium disc magnet onto the
the middle of the dish of mercury. When the head of a steel screw. Hold the
wire and the mercury were connected to a screw up to a D-cell battery so that
battery, the wire started moving around the the screw’s point sticks to the
magnet. Today’s electric motors are based battery’s positive terminal. Touch one
on this discovery. end of the wire on the battery’s free
terminal and the other end against
Dish of the side of the magnet. The screw
mercury with and magnet will start spinning.
magnet inside

Faraday’s motor

TOP TIP Nail
sp ins
Irfiegymnho1uot0uasusgdmciginnizashgmeenctwa’tt(mto0hshg.aitf4aeleaigttticnnstihkseht)oitenplollsdeofbbiow1noea5dsftientytoaregemfrrbautysidalhu,or.emtry
Magnet

Only one half of The moving part of 4 Stick the magnet to
one end of the a motor is called the side of the battery.
wire is coated the rotor Hang the coil in the
in enamel paper clip hooks and give it a
spin. The coil should continue
spinning. If it doesn’t, try
moving the coil closer to the
magnet or try using a more
powerful magnet.

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5 ThewnoartludralSadaocwsinsuieodcrensrovlcebdveeelevrwtryeetioteesxhusprfilnlrdaacoginrbmnodesipndilshniik,osivteewpea–rwnestthideietoehi.vcnoIewttsu’nshttmhohtyeehlaoeaeruwdnwaetpawooapnretlldidhimacewnmaarc,gnoeeiran!gknoersSdfo,wcswapichesrianmeowttntoieefctrihclceelet.

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Undperressure YOU WILL NEED:
to day.
TYahnoeuinpcsraternus’tmsufeerneetloictfactllhheeadnaagiribnaagrr,oobumuntedyteourus. rises and falls from day making Bowl
can see it happening by Large balloon
Scissors
Sticky tape
Two drinking straws
Sheet of card
Marker pen
Ruler

20 mins

Measuring weather 1 Cut the neck and a small part 2Make a short slit in the end of 3 Fold the card in the middle
of the body off a balloon. Stretch one of the straws and insert so that it will stand upright.
the rest tightly over the top of the other one into it. Tape Mark a scale on it with lines
the bowl as if you are making a them together and then tape one 6 mm (0.2 in) apart using a pen
drum and tape it in place. end to the middle of the balloon. and a ruler.

4 Put the bowl on a shelf and The straw moves
position the scale by the end of down if the air
the straw. Check every few hours
to see if the pointer has moved up or pressure falls,
down to show a change in air pressure. and up if the
pressure rises

how does Cool air sinks
this work?

WoCftbrfgohinroasaorreeemrlrtmdohmam.imetAnaaeoagiiegrrrrihertrtiapeioshgetrruheh,xhehnipeps-egddpsuaahiafrusnv-bfiererphideseeriirssslnreeo.augnaspwIlrtscsnrei.otseuedTizsirncnierhosnkiatisinoasnsupeergsritseasehet,andoseskr.dosenaTbwuwdpoholriunrowenewecw,dnosmlit,n-snhaapagoenestrssrhdetesahwesmtmearsliboooniuarpawnrdrkperlegel-ioarnpeosezlogrwrsnosenutsntatshhruhseyseeerke.sueoiwTprngbefthoihrlnotoeoziehdnfwuoret.yennesoaderiusi.,rr, Warm air rises

Cool air moves towards
low pressure area,
causing wind

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Wind YOU WILL NEED:
Whizzer
Four paper cups
Whaorionmudenmsdpaiendeaedcviisercrmsleieo. aTns,huaersier dtshpbeeyewdainsddheovwwichseiphcsoawbllyefdaitsatmntahakeneewsmintohdmeisectbuelpors.wInwinhgthi.zisz Paper plate
Felt-tip pen
Stapler
Pencil with an eraser
Drawing pin
Modelling clay
Stopwatch

20 mins

1 Take your paper plate and 2Arrange your cups so that
draw a cross on it to ind they are all facing the same
the centre. Mark one of direction on the rim of the
your cups with a thick stripe paper plate. Staple them in place
using your felt-tip pen. at the four points of the cross.

3 Push a drawing pin through
the centre of the cross
into the rubber on the end of
the pencil. Test the cups to make
sure they can spin around easily.

SCIENCE AROUND US Isobars
Meteorologists measure the air pressure in
lots of different places and mark the results
on maps. Areas of similar pressure are linked
with lines called isobars. These lines encircle
areas of high and low pressure. Where there
is a high, there is usually dry, ine weather.
Lows usually bring rain. Where the isobars
are closer together, the wind blows faster.

4On a windy day, stick the pencil into a The wind fills
big lump of modelling clay and watch the the cups and
cups spin. Using a stopwatch, count how p ushes the
many times the marked cup passes around in plate around
a minute. The more revolutions per minute, the
faster the wind is blowing. 121

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create a YOU WILL NEED:
cloud
Large, flat-sided jar
CimCnlroicceuoradoltdssecafyooirorpmuhicrigwohswhpaeenbncowkwvsiesapottsehfreodefguvcrsaoltop,uuontdrhdaef.trnTeoismncfyorimcodemreo, wptthloeaegtteseortco,hefaeawnrndastotsaemnrfodofrokcmreom.nadaerconlousuendds. Warm water
Resealable bag
Ice cubes
Black card
Match
Sticky tape

10 mins

Condensation 1 Tape the black card to the jar Make sure that
to create a dark background. the ice bag won’t
Fill about a quarter of the jar fall into the jar
with warm water from a tap.
Water vapour
condenses when
it hits air cooled

by the ice

2 Fill the sandwich bag with 4 Quickly put the bag
ice cubes and seal it shut. of ice on top of the
Make sure that it’s big jar and watch as a
enough to cover the top of the jar. cloud forms inside.

3 Get an adult to light a Some of the
match and then blow it warm water
out. Wait for a second or evaporates
two and drop it into the jar. and rises

122 TOP TIP

mjaAtwawrf.kittoIeehfrbbystbeeooulfouroaoewbmrdeyloieunondcgut’rothoowwspsuaempatieiittntoh,atgkeyhesioetmeuaiccn’anlloltotdoencuwnhdtdhd,.ooenur ’pt

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WorldMags.net
SCIENCE AROUND US
how does
this work? Types of cloud
The three main cloud types are cirrus, cumulus, and stratus.
WewmnvThsaweafuiaieonrtepassmenrydottmsenordcaarauwcouaitcrdsehsnelcorrateedsoillsniropeipadeestuanlonsedtrssad,httaeu.risieceltbrI.lbnlfoeevewaTawxastcchcahppoeeikretnaommhtdinujoentaeerhdrtorsdvsoe,scpatswabiaaalpcmenyainkorlttiodscsuqeatkuoorurcbcenntitovubdoldpaaioie.lgedpasclfBshnoroocuttusrunui,oepctendrsnlttteioeahhdnhislnmneeeettsdlfnhyhdewreseoetcoaiuaiminanwrtfrtentinmttaoothrhhtcniieemenlaeolritnawoonocmuvinldlraeaoc.taseitcpluAnteencutodysrioshlu.e–etrhsa. ect Cirrus clouds are thin, wispy, and high in the sky, cumulus clouds
are puffy and white with a lat base, and stratus clouds form
layers or blankets. But these clouds come in many variations.
Clouds with nimbus in the name indicate rain. In the right
conditions cumulus clouds can grow taller and taller, forming
giant cumulonimbus thunderclouds.

Water vapour
condenses around
tiny dust particles,
forming clouds

Cirrus – thin, high clouds that form wisps and curls

Sunlight warms Warm air containing
the ocean water vapour rises

SCIENCE IN SECONDS Cumulonimbus – storm clouds that tower up to 16 km (10 miles) high
Cumulus – fluffy white bundles of cloud that can grow upwards
Water in the air
All air contains some water vapour. Water vapour is a gas
and you can’t see it, but by making the gas condense
you can show that it is there. Fill a glass with crushed
ice and add a tablespoon of salt. The salt will make the
ice melt, drawing in heat from the surrounding air. This
lowers the temperature of the glass so much that frost
crystals grow on the outside. The water vapour in the air
has turned to ice. If the glass wasn’t quite as cold, the
vapour would condense into water droplets instead.

The glass is so
cold that it
makes water
vapour in the
air freeze

Nimbostratus – low grey stratus (layer) clouds that threaten rain 123

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sow a seed YOU WILL NEED:

Fiitnnohatrioscwteliivefxeeep.keaBsrniu,dmmt bewoennhgtteiyhnnostt,uoho’lelrgbrecoeovwenand.bSilyteioeot,anowrsssha,eaarete’ssfreoiggerohdyitonciugtarwnosneirlel?lfbm.Wuaristinht TOP TIP Jar
Blotting paper or kitchen towel
wassratBeetatheercrloidaxthsaptsrgtigedemrh–exorbeepi,twmemhwseaieernthndiynomgiectsagfevhewlaelenemstrilttdoatmhabspkaiked.ennaecBiadrfdsauetfiteeuftihtgfr.syeeereeoernaseutatsehntyceetfadytonosr Broad bean seed
Water

1 week

Germination 1 Soak your bean seed in water 2Fill the jar with the rolled 3Add 2 cm (0.8 in) of water
for a day or two. Dip a piece up paper and wedge the to the jar, but only to a level
SCIENCE IN SECONDS of blotting paper or kitchen broad bean seed between below the seed. Place the
towel in water to moisten it and the paper and the jar about jar in a warm, dark place so that
then roll it up. halfway down. If the paper won’t the seed can germinate.
prop up the seed by itself, pack
Up or down? some more paper inside the roll.
A plant’s roots will always grow downwards. Soak a
bean seed in water for a few days, then push some how does
lorist’s wire through it. Put some wet cotton wool into this work?
a jar and attach the wire to the lid. Lay the jar on its
side for a few days until a root sprouts and grows Germination is the production of roots and shoots from a
downwards. Then turn the jar so that the root points seed. In order to grow, the seed needs water, sunlight, and
upwards and observe it again in a few days. The root warmth. A seed contains food stores called cotyledons that hold
will have changed direction. Gravity pulls a hormone all the energy it will need. When the seed absorbs water, it is
called auxin in the plant downwards. If more of it prompted to start using its food store and swells up until the
collects on one side of a root, the root grows faster seed coat cracks. The plant embryo inside the seed begins to
on the other side, turning it downwards. grow – the radicle (embryonic root) forces its way out and as it
grows downwards, the plumule (embryonic shoot) emerges and
begins to grow upwards.

Cotyledon Seed coat is a
protective shell

Radicle Plumule
(root) (shoot)

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4Leave the jar for a few days, Cold storage SCIENCE AROUND US
keeping the paper moist by To try and prevent plant species from becoming extinct, the Millennium
adding drops of water if it Seed Bank in Kew, England, holds 1.5 billion seeds from around the
feels dry. Eventually, a small root world, making it the world’s largest wild seed bank. To preserve the
will sprout, growing downwards. seeds for hundreds of years without them dying, they are dried out
and frozen at -20°C (-4°F). To make sure that the seeds are surviving
the freezing process and will be able to grow in the future, a sample
of the seeds are defrosted and germinated every 10 years.

Growing race SCIENCE IN SECONDS
This experiment takes seconds to set up, but you’ll need to
monitor it for a couple of weeks. Fill three pots with soil and
plant a sprouting bean seed (step 5, left) into each of them, with
the seed and roots under the soil surface. Label the pots 1 to 3.
Place pots 1 and 2 near a window and pot 3 in a cupboard. Water
pots 1 and 3 a little every day for 3 weeks. Pot 1 will have grown
the most because it has light, water, and nutrients. The other two
won’t have grown much, or may have died, because pot 2 had
no water and pot 3 had no light.

12

5After several more days, a
green shoot will sprout from
the bean, growing upwards
seeking light. Move the jar into a
sunny spot to help the shoot grow.

3

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chasing the YOU WILL NEED:
light
Shoe box
GtThrheeeyeynwwiplilllalbenevtnsednaaltnwhdraetyausdrngtrihnoewoirrdwtoeawrytaotrhdgrseotuthcgelhosaseumrntaliogzheat!s. oIfunrceeceosfsliagrhyt,. Cardboard
Scissors
Black paint
Paintbrush
Sticky tape
Flowerpot
Soil or compost
Runner bean seed
Water

photosynthesis 1Cut a hole in one end of 1 week
the shoe box. You will also
need to cut two cardboard 4At the same time every day,
squares slightly shorter than open the shoe box and add
the width of the box. some water to the pot to keep
the soil moist. After several days, a
2Paint both sides of the squares shoot should emerge and eventually
and the inside of the shoe box work its way out of the box.
black to help reduce light
relection. When the paint has fully
dried, stand the box on its end and
tape the cardboard squares inside.

3Fill a lowerpot with soil
or compost and add a
runner bean seed. Give
the whole thing plenty of
water. Put the pot in the
shoe box and put the lid on.

SCIENCE AROUND US

Following the Sun
Some plants hold their leaves lat so
as to catch as much light as possible.
Others actually move so that they point
towards the Sun. It’s easiest to see this
in plants that have big, lat lower heads,
such as sunlowers. These plants with
bright yellow petals move their lower
heads to follow the Sun’s position as it
moves from east to west during the
day. This is called heliotropism.

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starch WARNING! YOU WILL NEED:
test
fBtilihoaneemdaviinmaoewendrayeyiibnsltclle-hepav.inoraeTeginnshfdotuteihnllasaawohtltcueoitiosdtuhhlatadtoonhrluoedeicsnawhal,eyelaicxlsblnot.sedrhteoautmhlisneaeenldyd Two dishes
Iodine and dropper
Through photosynthesis, green plants use sunlight to Glass jar
make food, which they store in their leaves in the form Saucepan
of starch. You can prove that photosynthesis has Rubbing alcohol
occured by carrying out a simple test. Black plastic
Geranium
Sticky tape
Tweezers
Scissors
Water

2 days

1Place a geranium in good 2Ask an adult to heat 3Use tweezers to dip
light. Wrap some black some water in the the wrapped leaf and
plastic around one of the saucepan and stand a regular leaf irst into
leaves and tape it shut. Leave your glass jar inside. Pour the water and then into the
it there for at least two days some alcohol into the jar alcohol for a few minutes.
before unwrapping it. and when it has warmed This strips the green
up, remove it from the heat. colouring out of the leaves.
how does
this work? 4Dip the leaves once more into the
warm water to remove any alcohol
AccwtPcsiWpphranoauelepharaltlrllnvealolletonaeaeelskditpstcngdgaeeositptldhlpnnssu’psusietcyhsnchost,netaogohteonobtbhtsaothaoleetioceitflehtginlos,rtscessehoydyanttieatsapnainsvtnlf.ltrotrihesgockhceIwaromeghhenttmdaders,hew.ioylispiasrlenAssawgossk.enstysieheTodltpt-coioeorghrefehliomrwoahetcrmaohofntynhaonfetdodgorougrstdnemcuhbwsuecsereteeysgaianlbatcrlarstahcsgbnedharteo,odiepsseltnllahmnwelorgiptenogeduhed.rndcphreeltIaieelttoervisurolnussxiietggsxsdpatintydihruhntocetsicen.hne.d. and place the leaves in separate
dishes. Drop some iodine onto each
leaf. The unwrapped leaf will go
dark but the wrapped leaf will not.

Cells on the dark Wrapped leaf
side expand does not
darken in iodine
Direction of sunlight
Unwrapped leaf
Normal-sized cells goes dark when
you drop iodine
onto it

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SPLIT COLOUR YOU WILL NEED:
FLOWER
Two glasses
Peaalvnaleiontrttthlseseebpreirctnooodlafoupucflrelao?nwfYtloeoswruceitcehransanctienmi.saahkllaeclfoonoloenueirfscy, oobluouuturnhdaaevnredstyhaoanuldf Food colouring
A white flower with a long stem
1 Take a long-stemmed white 2 The cut should extend about Sticky tape
lower – a carnation works halfway up the stem. Wrap Knife
particularly well – and lay it a piece of tape around the Chopping board
out on a chopping board. Ask stem where the split stops, to Water
an adult to slice the lower’s prevent it from splitting any further.
stem in half lengthways. 1 hour

3Fill two glasses with water
and add food colouring to
one of them. Place the
lower in the glasses, with half
of the stem in each.

transpiration how does SCIENCE AROUND US
this work?
Conserving water
PtcwlIstrenehlatahaelentlnevsmhstreoispetssthiohsdsealeriorxskttraemepefwhdopeetararhtumliohrfmipsarfroateewmietunctdaeagute,.tvkbhievtHaeehretpsa.hesfolrTetfoschrhoamstoeeefttleemoxtwtshmhyua,elieresetobeflmsdrsyrooptwswtrirllhiaiusatetenchetrsseksrxoroprye,muuitlcrsephgeoeomehsrtiveh.owte–eLnhwasolsexytatscieyrathilrlenecreaordgakmlforurewaotpdwtswoaf.athtnthtIethotheeureleirlspfosraltwoetenhmamdev.tehse Plants in dry places make the most of the little rain that falls.
flower’s petals change colour. Their leaves may be waxy to reduce water loss, or have
hairs to trap dew. Some plants store water in leshy, spongy
Water evaporates parts. Desert cacti store collected rainwater in their stems
from the leaves and have hard spines instead of leaves.

Water rises Tubes called
through the stem xylem carry
the water
Roots draw up
water from the soil

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SCIENCE AROUND US

Transpiration on the rise
Transpiration is an important part of Earth’s water cycle,
moving large volumes of water from the ground to the
atmosphere. A single sunlower transpires 1–2 litres
(2.1–4.2 pints) of water every day. A ield of corn transpires
up to 15,000 litres (31,700 pints) of water a day. The level
of transpiration in the Amazon rainforest is so great that it
creates a visible mist above the canopy, and is partly why
the rainforest is so humid.

Half of the
flower’s petals
change colour

4 Check the lower’s SCIENCE IIN SECONDS
petals about every
15 minutes or so.
Eventually you’ll ind that
half of them have turned red.

Dye travels up
the flower’s
stem towards
the petals

The more dye there Streaky celery
is in the water, The pipelines that carry
water (xylems) are visible in some
the stronger the plants. Pour a little water into a jar and
effect will be add some red or blue food colouring.
Stand a stick of celery in the jar and
leave it for a while. Check back at
regular intervals and you should see
the colouring rising up the stem.

The dye
rises up

the stem

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revivecaarrot YOU WILL NEED:
Cswwiteeaaimlslttseeia-rripng.—eTrlerthimvoaeintpemgwaasobatsvlhyeeti,nhtmogwrosefhuinrihcgmtahhov,ufmebpwuetaathatidisnenrsraoltiobtnhhpairnaoyrgtrucisegiat,rhroatraorollomtlma.weregsmmesbrbormramanoneeleemiscs.uocTlelaehslcleedudilmseossesomm–lvbeosrdsuaicsinnh,eathanisesd
One limp carrot
Glass
Toothpicks
Straw
Modelling clay or wax
Sugar
Water
Pen

2 hours

1 Take a limp, old carrot and hollow 3 Dissolve a teaspoon of sugar in Level of sugar
out a small hole in the top. Insert about a tablespoon of water and solution in
a straw into the hole and seal put some of the solution in the the straw
any gaps around it with modelling straw. Mark the level on the straw with a rises as the
clay or melted candle wax. pen. Wait two hours. The carrot itself will carrot absorbs
be irmer, and the level of sugar water more water
2 Stick a toothpick into either side of in the straw will have risen.
the carrot, near the top. Place the
carrot into a glass three-quarters Straw contains
full of water, so that the carrot is mostly sugar solution
submerged, with the toothpicks
resting on the rim of the glass.
OSMOSIS

SCIENCE AROUND US
Standing tall
Trees stand up because they are made
of stiff, woody material, but other
plants rely on water pressure. Their
cells are blown up like balloons, but
with water instead of air, absorbed
through the roots by osmosis and
pumped all through the plant. If the
cells don’t receive water, they become
limp and the plant wilts. The leaves
droop and the stems lean over.

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ABSORBENT YOU WILL NEED:
EGGS
Two fresh eggs
Wmasecohmtevioein-nspwebtryaomtwedearoarinbdmglseovatmheneesmemtxbhporreaosrnutimegc,heobnnuatctestwoneitmtgrheai-ttepetgedogrismts.oyeAoluauntbihloeeangv.mgeYeitosmousrbeucrmararnnooeuvs,neeidtteehadetlhwsbishayeyilnasl. Vinegar
Water
2 Put one of the eggs into a glass of Treacle or corn syrup
water and the other in a glass of Two glasses
treacle or corn syrup. Leave them for
another 24 hours. The egg in the treacle or 2 days
syrup will look considerably smaller than the
egg in the glass of water. Remove the eggs JEt of water
from the glasses and rinse off the treacle. sp urts out
of the egg

1 Place two eggs in a bowl and submerge
them in vinegar to dissolve the shell.
This will take at least 24 hours. Remove
the eggs, which will feel soft and rubbery.

how does
this work?

Isssflnoeooolmlwuustitm-iifooproonnemsr((miwwso,ieittnwhahebafmetlteoewormtrehetrreeaddmvoiissebtshslrsoaoelnflrvvreoueemnddtotmimalatoolhmelleeesoccscruuoeclleneocscsno)e)c.nnteWchtnerraaotnrttuateirogtraenhwtdeiaisdll
the same on both sides.
Water molecules move 3 Place the shrunken egg in
a jar of water and leave it for
through the membrane a few hours. The egg will swell
up as it absorbs the water – so much
so that if you prick it with a pin, a jet
of water will squirt out.

Dissolved molecules TOP TIP
cannot pass through
syhAaAoetffhculttle,eeerwrtrecmictyghahuogilaccecuscghihu.’eivadTmixwesinhpinwaseceettadnrvhreiriimyornpwbrepttoeehhgelnnoieegadatsyhrtsttteo.bhhhthreeaisneelvmelameade,kniwsshaesogedgowaiogglivwnh’sens.
Wpimiectenaxogfihostprgrehrsnmeaneetnsoecdtsdyhro.ttsrferhnruWaoeacplwimasemsstnyriephttitrshrrrauaceieanbpta.lkegss,rSsdoroalaiomrbsspctbeusioawslcagnsiawnarasclstuyeraeo,sdptsnaeetolthafrrl.rdwauceoAetetameci-ndotsdaenethrirhsnr,geopeumglwltgae’casiasadnakstrcreieetrnesrrogs,eoglltgwsalfutir,cnhaoitnmlitetemooewanloretkt.ahrhvitneeeeglr

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rapid YOU WILL NEED:
response
Paper
WhbMfarehieseteawnnsidneussserotentamonyyestooeturhuereirnarwgecbhatrhoiacoaitnhnpiosapnsrebesntechasece,naihvdfuoianscwsgeotemqitsnuhptfie.acorrkreemlytaischtaeioanmnyswpoaluniittdhresteaahcccototsi?nnegdNoofdo-yenoolnauieytr. Scissors
Sticky tape or glue
Pencil
Coloured pens
Ruler

30 mins

senses 1 Place a ruler on a sheet of 2 Stick the whole strip to the
paper and draw around it with ruler with either tape or
SCIENCE IN SECONDS the pencil. Cut this strip of glue. Ask a friend to hold
paper out and divide it into six the top of the ruler so that the
equal bands. Shade each of bottom end is hanging between
these a different colour. your open thumb and foreinger.

Trick your taste buds
Your brain works very quickly, but it uses
information from all ive senses to interpret
the world, and sometimes our senses
mislead us. Fill three cups with different
clear izzy drinks and get a friend to taste
them and guess what they are. Tell them to
leave the room. Add different food colouring
to each one. When they taste them again,
see if their answers are different.

Stump your sense of smell
Our senses of smell and taste are
very closely linked. The tongue can
only identify sweet, sour, salty, bitter,
and savoury tastes, but the nose is
much more sensitive and helps you
to identify things in more detail.
Cut a pear in half, hold it under your
nose and take a bite of an apple. It
will taste as if you are eating a pear
because of the stronger smell.

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On your marks... SCIENCE AROUND US
A fast reaction time is crucial in many
sports. A sprinter who reacts to the sound
of the starting pistol faster than other
runners gets away from the start line irst.
Pitchers in professional baseball are able
to throw the ball at a speed of almost
160 kph (100 mph). This means that the
batter has to react and swing the bat in
less than 0.2 seconds to stand a chance
of hitting the ball effectively.

Drop the ruler
without
giving any
warning

The ruler how does
falls quickly. this work?

There isn’t When you see or hear something happen,
much time to the information has to travel from your
eBoyreehfoseroaerrdyeo,aaurssciaaglnnoanalgchtnaoesnrvtwoehstratatovyetohl uefr’ovbemrasiyneo.eunr
grip it! brain to the muscles. All of this may
happen in just a fifth of a second – this
is your reaction time.

Brain processes
information

Eyes see
something
happen

3Ask your friend to drop the Muscles receive
ruler, without warning you. signal from the brain
When they do, grip it as fast
as you can. The fewer bands that
slip through your ingers before you
grip it, the faster your reactions.

133

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drum up dna YOU WILL NEED:
some
AtcDelhlNllasAliinvtfi-hnrloiegkmmecmceheloolsllwlesccatuonolnedtgacsraieonlewleaidtaDwsneNdittAhfou(ydfnoecuiontrixsooytnwrr.uibnTcothenioiysunecscsle,owidociertahcigstiedhsn)i.steYoteoricxeupdcceaoorinndmeeea,xnttlrtoha.nacgtt Strawberries
100 ml (3 fl oz) water
WARNING! 100 ml (3 fl oz) rubbing alcohol
Washing-up liquid
suhocwsioeagyendsholRlcl-usayuevusmbnferilanbtangurnhimitanscialttagaamlieonnltaeastnetlipdbcsvhoiloeeereafhipr.trpfo,etUduuiclacrm,sroi,aeneaneblknsiatsutoadi.lttcoi.nkdiontIsnothliysoioanswiltno.haonItiatlxgsiihocs, Salt
Large bowl
Two jars
Fine sieve or strainer
Thermometer
Fork
Paper clip
Spoon
Jug
Glass

1 hour

DNA 1Before you begin, put the 2In a second jar, mix the
alcohol in the freezer for water with a few drops
30 minutes. Put some of washing-up liquid and a 3Combine this mixture with
strawberries in a jar and mash pinch of salt. Stir them together the mashed up strawberries
them up with a fork or the back of slowly so as not to form bubbles. and mix everything together
a spoon until they turn to pulp. Scoop out and dispose of any slowly and carefully for about
bubbles that do form. 2 minutes. Again, scoop out
any froth if necessary.
4 Pour some hot water into a
SCIENCE AROUND US bowl and, if necessary, add
cold water until the temperature
is about 60˚C (140˚F). Stand the jar of
mashed fruit in the bowl and leave it
there for 15 minutes.

Design for life TOP TIP
DNA is like an instruction manual for cells.
Everything about a person, from eye and fryueoaixtunapsnreoaedrnnmimisYdoeoonevevu,neeatwgcntweahhdtniieactahphbsevlkaewarisnfkrooi.iperwrEkrmtxoisy,pvatboeihdefbriissionamttgn.heatennhrtaa,t
hair colour to the likelihood of contracting
certain diseases later in life, is contained
in his or her DNA. Apart from identical
twins, everyone is born with unique DNA.
It is found in every cell, so DNA can be
extracted from samples of blood, hair, or
saliva found at crime scenes. The unique
pattern of the DNA can then be recorded
as a series of rungs, almost like a
supermarket barcode, called a DNA
ingerprint. This can be compared with a
sample taken from a suspect, or stored in
a police or government agency database.

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how does The white
this work? blobs contain

DmuwSiichtnspNhaoeaetpaolAmsilttlithaexhmabiecmd.isnrkTlafaaaguserkhnyktu-pdeeoueeeistlrprisienaukataednlspehnibqqidedddatouuhee(DevwitiedneewnNtapicrnipitrAunsehmywlntae,cteoigihnXnltdsfushetg-odmilsconamliihuetfpfdfeailtbextlditasphortroe)ceueeengrahnard,leestakcsctossdcadhtetrhldrtiedlolshuleeer’onssacdmraowgttninuali,synvcudrooedeacttuhustslholsheteeuetccuehbraacsealncl,eelleeccplsldleorlewolhwelctaomehalilltcrlse.oplt.,mTemuMahdlbnloesarbdssaDiyothntmNhuaieneApsegc.se,ll the DNA
code that holds the
genetic information.

Uncoiled chromosome shows the
double helix structure of DNA

5 Push the mixture through a 6Take the alcohol from the freezer 7Almost immediately you should
ine sieve or a strainer into and dribble it down the side of see a white, web-like layer forming
a fresh glass to ilter out all the glass very slowly so that it between the liquid and the alcohol.
of the lumps. All you should have settles on top of your mixture. You Blobs of jelly-like DNA can be picked up
left is the liquid – this is where might ind it easier to use a jug or to on a hook made from a paper clip.
the DNA will be. add the alcohol a spoonful at a time.

135

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GrowowynouGrerms YOU WILL NEED:

Lyawdiorfoaeeunsacc’htlaolnyanmeor’teeouudsursntihundoaaau–nllylsdlb.sssuT.hethIaetfephtyyeihsoaseuermaexcnp.taMdhenerisc’itmirrzeoseeaessnsce.tooSwanponiiymclylomoeudraiglarikvtar,eeinnyigaysolomwutuhsaimtnychgisaignslbhlkeaetdaritneghbgaiasntiocnkot!ltedyinrotiyaou 1 litre (34 fl oz) water
15 g (0.5 oz) agar flakes
Two beef bouillon cubes
Small, shallow dishes, which can be
thrown away after the experiment
Clingfilm or resealable bags
Bleach (to kill the germs - adult use only)

1 week

Bacteria 1 In a pan, mix the agar lakes 2 Let the mixture cool for 3 Immediately cover the 4 To begin the experiment,
with the water and two bouillon 10 minutes. Make sure that dishes to keep unwanted uncover a dish and swish
cubes. Stir it over a low heat your shallow dishes are as bugs out. Slide them inside a ingertip lightly across
until everything dissolves. Bring clean as possible. Ask an adult to plastic resealable bags or cover the surface of the mixture. Cover
the mixture to the boil, then let it sterilize them with hot water or in them with clingilm. Let the the dish up again straight away
simmer for 30 minutes (to sterilize the oven. Pour the cool mixture dishes stand until the mixture has afterwards. Use each dish to test
it). This mixture provides food for into the dishes so that the bottom set. Agar usually sets quickly a different person. Label them
the bacteria and helps them grow. of each dish is covered. without having to go in the fridge. so you know whose is whose.

how does TOP TIP
this work?
Avcsgeatuihnaognsoreetsbphitdesesaetu.rtmpiPofIsatouaeensiordstectdrseohutiusdasftcbrlheisiussokeedthlmetdientuinujsurisentecteletrlohhaibieefeoawaosnaktc.retilstIntegtmechgdeiriseefilaaaaondas.tnotiliusdnidasomets,
A1YlTfifdaocr,oon0oristavuuesg0imnincde0csogshriootfntleihetinutgmeomehglbdeiettaanahthmsnnghceetyeeaswtmgevdrmmaorreimoaisgaurialwhsalilmslxgi.eroaetaiTrnnumecibhtnsrohoieoaexnoaan,cntbsnrnueateieadrnesapewrcvtdialsatesatiegttrlincohhanra“eifengbacitnjyhsltuiuefl.hfelelsmeitAeoceutnrnfuensdrotaellesttnlkbb”hirfpeeoa.yreadlofcytyaimbtfneeebibanyywrseacieanoccnt,deureofbbaarrmlmliouinyan–bmtesigmte,wahvrtynbaaihhsobulote.eiutybuynrrretlioeeu.nts

Whiplike threads
used for swimming

Tough cell wall forms
protective outer layer

Cell membrane Inside the cell are all
the chemicals that
136 help the cell grow

Bacterium

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SCIENCE AROUND US
EUREKA MOMENTS Antibiotics
Bacteria Medicines that kill bacteria are called
Bacteria are found everywhere on Earth. antibiotics. Before they were discovered,
They loat in the air, live in the soil, and are there was little defence against harmful
found all over plants and animals. Most bacteria and a simple infection could
bacteria are harmless, and some are vital to be fatal. The irst modern antibiotic
life on Earth, breaking down organic waste was discovered by accident. In 1928,
and helping plants to take in nitrogen from Alexander Fleming (1881–1955), a
the air. But a few can be dangerous. medical researcher working in London,
They can cause food poisoning and noticed that something had gone wrong
serious diseases. The bacteria pictured, with one of his culture plates. It was
Streptococcus pyrogens, causes skin meant to be growing staphylococcus
infections, sore throats, and scarlet fever. bacteria, but a mould had grown on the
plate and killed some of the bacteria.
He named the active substance in the
mould penicillin and the antibiotic of the
same name was developed from it.

5 Leave the dishes in a WARNING!
warm place. After two or
three days you should see HdacEpstinlspshiLltnadperaePgec,orrEfeiwetssoifeRelneomuitdtndhrssho,gtehooodSfietlmoffluohtontfuhttrmettnilhoendcohsoeeuaesbbutwgue.bllndoeheOasxacipaoaisspcnnoecuchhetcgvhnhteereyeisrstmatforihpth.oanuhteAleeradhrecnnaseebahdtehnxaa,naidxepsygdnhipchsesosudoea,ehrulsuoictursemr!irrass.ms,AeDrehttesaeDnhoolfknietUunug.etnl’LlhdAtlhyTttthablyese
something on the surface of the
mixture. See what has grown
after one week. Whose ingers
had the most bugs?

Big colonies The bouillon in
contain larger the agar mixture
numbers of provides food for
ba cteria
the ba cteria
137
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WHorOldMMagEs.net
EXPERIMENTS

Science experiments are often confined to the
laboratory, but with a little ingenuity you can
achieve some spectacular results at home, too.
Whether you want to make endothermic ice
cream in minutes, create a floating compass
from scratch, or test Isaac Newton’s laws of
motion, our experiments have got you covered.

DON’T
DO IT
ALONE

USANUNDRIAFEEDRYYYUO1OOL8UUTU,’RMHWEAAITVKHEE

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140

Nine home
experiments

144

Make a
zoetrope

146

Making
hot ice

148

Penny drop
experiment

150

Double-slit
experiment

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DON’T
DO IT
ALONE

MHAAUVIWKFNEEYIDTASOHEUNURRYA’R1OED8EUYU,OLTU

HOME
EXPERIMENTS
Discover science in the most fun way possible – by
doing these awesome experiments in your own home!

If you’ve ever seen a picture of a medieval catapult microscopes and spotless purpose-built labs, but they
and thought it looks amazing but you’d never be made huge headway with medicine, geology, engineering
able to have one, think again. You can make one and maths, to name a few. With nothing but a plastic comb
in minutes! It’s just one of our great experiments you can you’ll discover how to bend a stream of water, and by the
do at home, no lab coat required. Not only are they fun to end of the article you’ll be flinging projectiles from your
do, but they will also explain some of the basic parts of our very own catapult – safely, of course.
everyday lives, like how magnets work, the forces that
help to create lightning, and the reason why plants will Science is fascinating, but it can also be delicious.
stop at nothing to reach sunlight. Thankfully in this feature you’ll also discover how to pour
Using everyday items like combs, rubber bands and an instant soda slushy and make ice cream in a bag in 30
string, we will demonstrate real science. After all, the minutes flat. So if you have an enquiring mind and a few
Greeks, Romans and Egyptians never had electron things lying around the house, why not leap right in and
give these experiments a try?

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Levitating ice cubes 10 Compass

Perform science-inspired magic by mins
sliding a string into a block of ice
Make a compass from
just a nail and a leaf

10 What Checklist What you’ll
you’ll learn
mins learn N ail
Magnet How magnetising
Checklist How salt Leaf an object can help
lowers the Bowl of
Glass of freezing you find your
water temperature water way around

Ice cube of water
String
Salt

Drop the ice cube into a glass of water freezing point of water. After a few 1Magnetise your needle
and lower a piece of string onto the top minutes, the salt will dissolve, which Stroke the nail with the magnet 50 times in
of the ice cube. Next, shake a little salt in turn enables the ice to re-freeze the same direction. Put a marker on the end
over it, which melts the ice. This is around the string, trapping it so you you’ve stroked toward to help you identify it.
because salt molecules lower the can lift the cube.

Conjure lightning

Create a small electrical storm in
your own kitchen

10 What you’ll 2Make your compass
learn Magnetic objects naturally point north.
mins Place the leaf and nail on the water so it can
Find out how spin unhindered until it finds the direction.
Checklist electricity is
created thanks to 3The science behind it
Plastic fork static charges and Stroking the nail with the magnet aligns
T in foil a conductor the atoms. It points north because that is the
Balloon direction Earth’s magnetic field lines point.
Rubber WARNING

glove WATCH OUT FOR
ELECTRIC SHOCKS.

MAKE SURE YOU
HAVE AN ADULT

WITH YOU

Wrap the fork in silver foil and rub the the fork. Touch the tin foil with your
balloon all over your hair, giving it a ungloved hand and take it away. A
negative charge. Put the balloon down small spark of static electricity should
and touch it with the fork, using your appear as electrons leap from the fork
gloved hand. This transfers electrons to to your hand.

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Checklist DIY catapult 20 Soundboard

B lock of How to defeat your medieval mins Discover how you
wood enemies with physics can manipulate a
guitar’s acoustics
S poon Adding a 1 Make
Rubber band sling on the the base Checklist What
end can send you’ll
x2 the projectile Select a G uitar
Drawing pin much farther weighty block P lastic board learn
Metal board
x4 D ecibel How
different
What you’ll as the extra of wood, about 2.5cm (1in) thick. meter materials
movement Wrap two rubber bands around the
learn creates even front, one above the other, secured reflect
more energy either side by a drawing pin. sound
How angles can
affect trajectory,

distance and power

2 Create 15
the
catapult mins
The best release

angle is 45 degrees, Slip a spoon in

exactly halfway The faster you between the wood and the rubber
between being release a projectile, bands, with the head pointing up.
vertical and the more kinetic This will form the main part of
horizontal energy it receives, your catapult arm.

sending it farther

Pulling the spoon 3 The Using a decibel app, play a note
back from the crossbar while holding a sheet of plastic
head stretches above the guitar and record how
the rubber bands, Build a crossbar loud it is. Change materials to see
creating energy by gluing two how some absorb sound and
pieces of wood to a horizontal one.
Use a protractor to see when the others deflect it.
spoon’s angle is 45 degrees and glue
the structure on either side.

Turn summer 2 What you’ll
to autumn learn “The best
hours release
Why leaves turn angle
Change the colour of leaves different colours in for the
autumn and again catapult is
Checklist in spring 45 degrees,
exactly
Leaves In a jar, mash up
Rubbing leaves with rubbing
alcohol. Put the jar
alcohol into a bowl filled with
Bag hot water and cover.
J ar After 30 minutes,
C offee

filter paper
Hot water

place a coffee filter in halfway
the solution. An hour between
later, the leaf will look

autumnal, as the being
levels of chlorophyll, horizontal
which makes leaves

WARNING green, .reduce in and
autumn, so other vertical”
RUBBING ALCOHOL colours can be seen.
IS DANGEROUS.
MAKE SURE YOU
HAVE AN ADULT
WITH YOU

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Bending water Hair doesn’t conduct
electricity very well so every
How to use electron transfer to make
water bend before your eyes time you comb it, you are
increasing static charge

5

mins

Checklist This makes the
comb negatively
Water tap charged as it has
Comb more negatively
Hair charged electrons

The comb and Rubbing the When the comb is near the What you’ll learn
your hair initially comb on your water, the electrons jump
have a fairly even hair moves off it and everything is How you can manipulate a
proportion of electrons to balanced again stream of water without
electrons the comb even touching it

1 Charge 2 Force of 3 Coming
the comb attraction together

Rub the comb on Start the water This desire to
your hair. This will running at a very slow transfer electrons
transfer electrons stream. The pulls the positively
onto the comb and negatively charged charged water
negatively charge it. comb repels some of toward the comb
As you are grounded, electrons will come the electrons in the water. This creates a when it’s held in a nearby position. The
from the ground and balance you, but the positive charge in the stream so it is force that attracted the two together is
comb remains full of negative charge. attracted towards the comb. called static electricity.

Ice cream 30 Instant soda slushy
in a bag mins
Turn your ordinary fizzy drink into
How to create ice cream a delicious brain-freezing slushy

Checklist 2 2 125t0tamabblellesmsppoilokoo/ncnssressuaagmltar What 2 Checklist Shake the bottle and
you’ll freeze it for three
Hv 2aanzlfililpateloecaxsktproafocrentezer bags learn hours B ottle of hours and 15 minutes
B ag of ice fizzy drink to create a slushy. The
How an ice What drink doesn’t totally
pack can you’ll F reezer freeze because the
rapidly learn sugars, flavourings
and carbon dioxide
reduce How bubbles lower its
temperature pressure freezing point.
affects When opened, the
Mibstnhhaiteoxgouitiacnoledzgtoicehprttaehlhvoaeeecmrsksteohbbcleeaoidcgmnoi.dfiPmi.leokLedueos.rarTctvochherleedeitsaiacatmnoeltd,fasrsnsleuiodegglzhisadeatr,lflaytroanirlnotdhhwtaoveealrafrntnsahiontlahltahnheoeeciucxroetramr,ntatepadcmlktepaeptueneitltdrytoahfputreuotofiurazeerrnssndto.it freezing carbon dioxide
rushes out, instantly
points re-raising the
freezing point.

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Re-create Make a DON’T
a famous DO IT
Victorian ALONE
novelty
toy with MHAAUVIWKFNEEYIDTASOHEUNURRYA’R1OED8EUYU,OLTU
just a few
household zoetrope
objects

Before the advent of motion Step 1. Okay, in order to start Step 1
pictures, animated creating your zoetrope you
characters were confined to need to take your white paper Step 2. Now draw (or print off) a horse
simple and novel toys, or strip and wrap it around the running, with each segment moving its
old-fashioned shadow plays. inner lip of one of the position onwards. Importantly though,
One of the most successful of upturned coffee can lids. If ensure that whatever action you draw ends
these playthings was the the strip is too long, mark the up as a full circle by segment 12, as this way
zoetrope – invented in its point where the ends meet the zoetrope’s animation will play out on
modern incarnation by and then trim off the excess. loop, with no break in the action.
British mathematician Next you have to take a
William George Horner in measurement of the length
1834 – which created an and divide your paper
illusion of movement from equally into 12 segments
the rapid spinning of static using your ruler and pencil to
pictures. It became an mark out each one.
overnight sensation and by
the 1860s zoetropes were Step 2
commonly found in the
houses of the wealthy and
privileged. Luckily, today a
DIY zoetrope can be made for
little to no cost at all, with just
a small selection of everyday
items. Try it out – they are
genuinely fun little gadgets.

You will need:

A3 white paper (cut Step 3
into a long strip)
A3 black card (cut into Step 3. The next thing to do is take your strip
a long strip) of black card and cut it down so it has the
2 Coffee can lids same length of your paper, but twice the
Pencil width (ie the height). You can do this easily by
Craft knife just placing the white paper over the card
Liquid glue and marking it with a pencil. Once this is
Ruler done divide the top part of your black card as
Scissors you did with the white paper, with small
pencil dashes to mark out each segment
transition. Extend the lines from the halfway
point to the top as shown.

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Step 5
Step 4

Step 4. Now, with your Step 6 Step 5. With great care, take the craft knife and score an X-shape
scissors, cut either side of puncture in the centre of the coffee can lid. Don’t make this any
each pencil line on the top of larger than a centimetre. Once done try inserting your pencil
the card down to the halfway through the slit. It should fit through and then get snagged on the
line so that you are left with metallic rubber holder on the end. If the pencil is a little wobbly
5mm (0.2in) gaps at each by step 7 you can always apply some glue or Blu-Tack to secure it.
segment transition. These
only need to be small so take Step 7
your time. If you’ve
completed this step-by-step
correctly up to this point you
should have something like
this. Now put it to one side.

Step 6. Now to assemble the Step 7. Finally, take your paper strip and insert it into the
zoetrope. Draw your pencil base of the structure, ensuring the horses face outwards
back out of the slit in the lid and that both ends meet without any crossover. Once
and place it to one side. Place satisfied with the fit, glue this in. Now place the second lid
the lid upside down on a on top, reinsert your pencil as before and grip it between the
level surface and squirt a palms of your hands. Rub your hands back and forth to
thin line of glue around its rotate the pencil and the entire zoetrope, while viewing the
inside rim. Pick up your horses through the slatted windows. Amazingly the horses
black card strip and glue it in are now one that appears to be galloping. Congratulations,
place, ensuring that the you have just built your very own zoetrope!
slatted windows are at the
top and the solid base at the
bottom. If you do this
correctly you should be left
with a crown-like structure
as shown here.

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The supercool Making DON’T
liquid that hot ice DO IT
instantly ALONE
freezes
at room MHAAUVIWKFNEEYIDTASOHENUURRYA’R1OED8EUYU,OLTU
temperature
Step 1 Step 1. First, a litre of
With this experiment, we Step 2 clear store-bought
will show that we can create a vinegar must be
substance that is a liquid at A measured out. This must
room temperature but that be clear, as brown
immediately crystallises vinegar contains
when disturbed, forming impurities that will
something that is known as prevent the experiment
hot ice. from working. Next, you
need to add about three
Hot ice is an amazingly cool to four tablespoons of
substance and the baking soda (sodium
ingredients required to make bicarbonate) to the
it are really easy to obtain. vinegar. This has to be
However, it is notoriously done slowly, as the
difficult to make, and you reaction can make the
probably won’t get it right on liquid explode over the
your first attempt, but don’t side of the container. Stir
give up hope. You can either this until all the baking
re-melt any failed hot ice or soda is dissolved and
start over again, making sure then put the mixture on
to follow each step in the to the hob to boil.
method carefully.
B
This is a great experiment
to attempt at home and an
even better one to try out at
school. If done successfully,
you can directly see the
effects of crystallisation –
there’s plenty of science
embedded into the fun of
seeing hot ice in action.

You will need: Step 2. You need to get rid of about 90% of the
liquid, so leave it to boil for over 30 minutes. You’ll
1 litre of clear vinegar start to notice a white substance on the side of the
4 tablespoons of pan. This is sodium acetate, and a bit of this needs
baking soda to be saved for later use. Eventually, a crust
Steel saucepan (sodium acetate anhydrous) will begin to form on
Container the liquid. At this point, take it off the boil and
transfer it into a container. This must be
146 immediately covered to prevent the substance
crystallising. You then need to cool it, so place it in
an ice bath for 15 minutes or a fridge for a bit longer.

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Step 4

Step 3

A

Step 4. The points where sodium acetate is introduced will begin to
crystallise. After a few seconds the entire liquid will appear to freeze.
However, when touched, the substance is hot and not cold because the
process of crystallisation here is exothermic, so heat is given off as the
liquid solidifies. So, what’s happened in this experiment?

Step 3. The liquid B Hot ice equation
needs to cool below
Na+[HCO3]– + CH3–COOH
room temperature. This

makes it into a

supercool liquid that Baking soda Vinegar

will exhibit the

characteristics of hot CH3–COO– Na+ + H2O + CO2

ice. Once it’s cooled, you

can take the lid off and

put some of the white Sodium acetate Water Carbon dioxide

sodium acetate

collected earlier in

the liquid.

Conclusion. Almost every substance has a freezing point, but for something to solidify the molecules must
rearrange from a liquid to a solid or crystal arrangement. However, hot ice, or sodium acetate trihydrate, is a
supercool liquid where the molecules do not rearrange until they are disturbed, in this case by introducing
sodium acetate. Hot ice melts at 58 degrees Celsius and is a crystalline solid at room temperature, allowing this
effect to be produced as the baking soda and vinegar are heated. The unarranged molecular structure results
in the occurrence of this crystallisation effect. You can re-use your hot ice by adding vinegar until the solid
crystals are fully dissolved and repeating our method again.

Conclusion

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Explore Penny drop
Sir Isaac experiment
Newton’s
first law of Step 1. Take your card and cut it A Step 1
motion with into long thin strips vertically
some easy- roughly 2cm wide, then tape the
to-find items ends together so it forms a hoop.
This experiment works best when
If you’ve ever wanted to test a the hoop is 8-10cm across.
scientific theory at home then However, for variables to the
now’s your chance. Sir Isaac experiment, take another two
Newton’s first law of motion strips and make one smaller hoop
helps to explain the motion of and one larger.
conventional physical objects
and systems. He implies that B
any object at rest will remain
at rest unless an unbalanced Step 3
force acts upon it.

So, if you were to place a
tennis ball in space and give
it a shove, its momentum will
keep it moving at the same
speed and in the same
direction unless something
bumps into it, and if left
untouched its inertia will
keep it in the same place.

On Earth Newton’s law is
complicated, however, by the
permanent presence of
gravity and friction, the
former constantly pulling
objects towards the ground
while the latter slows them
down. Does this disprove
Newton’s first law? No, in fact
these forces demonstrate its
high probability, as you can
see in this simple and
easy-to-conduct experiment.

You will need: Step 2. Next, Step 2
take your glass
1 sheet of card jar and fill it with Step 3. Third, put your water-filled glass on a level
Glass jar water roughly surface and then place the hoop on top of it, so that
Cup of water two thirds of the it radiates out from the centre of the jar like the face
Penny (any coin wil way up. The of a fan. Finally, place your penny on top of the
do, however this is water adds an hoop so it is directly above the glass jar. The card
caled the penny drop extra level of hoop should support the penny and maintain its
experiment!) data return, as form if done correctly. If the hoop deforms, you
Selection of other we shall see need thicker card.
coins of various sizes later on, so it is
Pencil best used.
Sel otape

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DON’T
DO IT
ALONE
MHAAUVIWKFNEEYIDTASOHEUNURRYA’R1OED8EUYU,OLTU

Stop! Science time! Step 5. Right, before moving on to Step 5
anything else, repeat the last step
So how does this relate to Newton’s first law? Well, currently the penny but this time use either the
is at rest, its inertia keeping it in the same place. Gravity, one of Earth’s smaller or larger hoop, or a
meddling forces, is also being counteracted by the hoop, which itself is smaller or larger coin. If replicated
fixed in position by the neck of the jar. With gravity taken out of the correctly, you should notice how
equation and friction negligible, Newton’s law is currently ringing true. the success rate of the coin
dropping straight down into the
Step 4 jar when using the larger hoop/
coin is less than it was before,
A while it is greater if using the
smaller hoop/coin. Finally, notice
how the coin’s speed decreases as
it travels through the water – this
demonstrates the increase in
friction when moving through
water over doing so in Earth’s
standard atmosphere.

Step 4. Okay, action time. B Stop! A
Take your pencil out and hook C Science time!
it through the hoop. Now move B
your hand into position so the When the original hoop was
pencil is hovering by either whipped away from the mouth of Conclusion
the right or left side of the the jar, the force counteracting
hoop at its equator. Now, in gravity was suddenly removed, While Newton’s first law of
one swift movement, whip the allowing it to immediately exert motion may initially seem
hoop to the side and off the jar its influence on the coin. The inconsistent with our
– just like a waiter whipping a speed of the hoop’s withdrawal experience on Earth, those
tablecloth away – and watch also mitigated the effects of experiences are in fact
the results. If you have friction on the penny’s centre of consistent. Simply put, an
performed this step correctly mass. Consequently, the coin was object will remain
the penny should drop left suspended in its current stationary or moving in a
straight down and land in the position in the air with just the straight line, providing no
glass of water, eventually force of gravity to pull it down in a auxiliary forces act upon it.
resting at its bottom. If this straight trajectory into the glass. For us on Earth, though,
does not happen – ie, the If the experiment were carried any object (including
penny falls to one side of the out in the vacuum of space, human beings) will always
jar – try again with a faster however, with no gravitational naturally be impressed
hand movement. force impressed upon the coin, upon by the forces of
this would not have happened. gravity and friction.
D
The increased/decreased
contact area between the hoop
and the coin affects the level of
trajectory-altering friction, with
the larger hoop inflicting more
and the smaller one less, as your
results should have shown.
Consequently, if there did not
have to be any contact between
the coin and the hoop, there
would be no physical friction –
atmospheric drag remains
though – and the coin’s straight
course would not be altered.

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Understand Double-slit DON’T
the basics of DO IT
wave-particle ALONE
duality
with this experiment MHAAUVIWKFNEEYIDTASOHEUNURRYA’R1OED8EUYU,OLTU
simple home
experiment Step 1 Step 1. Start by taking your laser pen and
Step 2 taping its On button down, so that you get
English physicist Thomas a consistent beam of light. By doing this
Young’s 1801 experiment into you will ensure that you don’t have to
wave-particle duality provided tamper with the setup when it’s action
the base for the entire wave time. After all, you will be firing the laser
theory movement, identifying pointer through three very narrow
the phenomenon of needles, and any movement will throw off
interference and the your results. Be careful while doing this, in
inseparability of the wave and order to avoid shining the light into
particle natures of light. Young anyone’s eyes.
observed that when light from a
single source is split into two Step 3
beams (through his two slits)
and then recombined, the
beams’ peaks and troughs
might not be in phase. This, he
discovered, was because when
a peak and trough coincide they
cancel each other out, leaving
an area devoid of light.

When two light waves meet
of the same wavelength in
phase (they have matching
positive or negative electric
fields), they will add together to
form a brighter light. However,
if they are out of phase, with
their electric fields cancelling
each other out, they will
combine to produce an absence
of light.

To test the theory ourselves,
we just need to take a short and
simple step into the world of
quantum physics…

You will need: Step 2. Next, squish the laser pen into a large glob Step 3. Now take your three needles and insert
1 sheet of card of Blu-Tack and then fix it to the bottom of an them side-by-side into the bottom of your second
(black) upturned foam cup. This will be your firing foam cup. This is harder than it sounds, as they will
2 foam cups platform, and it should look something like this. need to be as close together as possible but without
Laser pen At this point, it would be a good idea to measure breaking into each other’s puncture holes. If the
Sel otape the height of your pen, as you will need to position needles branch out at their ends, space them with a
Pen knife your needles at the same height. small blob of Blu-Tack.
Blu-Tack
3 needles WorldMags.net

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