awesome physics with tcer Alina-2019

SIMPLE CAMERA

Lens To focus a sharp image onto the film
Film To record the image
Diaphragm To adjust the size of aperture (control the brightness of the image)
Shutter To open and shut the camera (film is exposed only for a short time)

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(Understanding question)

1. Diagram 1 shows a convex lens is used to produce fire. The convex lens is aimed towards
hot sun rays. A piece of paper is placed under the convex lens.

Diagram 1

Explain why the paper burns.

- The rays of the hot sun are parallel / from infinity

- The rays will converge to a focal point after passing through the lens.
- Light / energy will be focused.

- Light turns to heat and produce flame.

2. Explain why the diamond is sparkling when the ray of light pass through.

- A diamond has a very high refractive index.

- Its critical angle is small.
- The facets of a diamond are cut so that angle of incidence greater than the critical angle.

- Total internal reflection cause the diamond to sparkle.

3. Explain how to use a concave mirror to heat up water in a container using solar energy.

- parallel light ray hit the concave mirror
- reflection occur
- all the light ray will converge to a focal point
- Light / energy will be focused
- Light turns to heat and produce

4. Explain how you would estimate the focal length of a convex lens in your school laboratory.

- The convex lens is aimed/focused to a distant object (infinity)

- The screen is adjusted until a sharp image is formed on the screen
- The distance between the screen and the lens is measured

- Focal length = distance between the screen and the lens

5. Diagram 2 a ray of light directed perpendicularly at a side of the semicircular glass block.
The ray passes through the glass block to a point O before leaving the glass block. The
angle of incidence in the glass block is 30°.

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Diagram 2
Explain how total internal reflection occurs in Diagram 2?
- Increase the angle of incidence, i then angle of refraction, r will also increase
- Keep on increasing the angle of incidence until angle of refraction is 90°
- The angle of incidence is called critical angle
- Increase the angle of incidence more than the critical angle, the ray will be reflected.
6. Diagram 3 shows a stainless steel spoon. When you look at the spoon, you will see an
upright and virtual image of your face on one side of the curved surfaces but an inverted
image on the other side.

Diagram 3

Draw a ray diagram to explain how one side of the curved surface of the spoon form an
upright, virtual and diminished image?

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7. On a very hot day, vehicle drivers often see images which look like pools of water on a road
surface. This phenomenon is known as a mirage.
(i) Explain how a mirage is formed.
The layer of air nearer the road warmer
The density of air decreases nearer to the road surface
The light travels from denser area to less dense area
The light refracted away from the normal
When the angle of incidence exceed the critical angle, total internal reflection occurs
(ii) Can a mirage be formed in very cold places like the Artic?
YES

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WAVE

Progressive waves Stationary wave
Gelombang progresif
the wave where the wave profile moves Gelombang pegun

with time the wave in which the wave profile does not travel
gelombang di mana profil gelombang bergerak with time

dengan masa gelombang di mana profil gelombang tidak merambat
Example: dengan masa
Contoh:
Example:
• Transverse waves Contoh:
Gelombang melintang Resulting waves in musical instruments

• Longitudinal waves. Gelombang yang terhasil di dalam alat-alat muzik
Gelombang membujur

WAVE

GELOMBANG

transferring energy from one location to another which is produced by an oscillating or vibration motion

memindahkan tenaga dari satu lokasi ke lokasi lain yang dihasilkan oleh gerakan berayun atau getaran

TRANSVERSE WAVE LONGITUDINAL WAVE

Gelombang melintang Gelombang membujur

Pattern of

wave

produced

Bentuk

gelombang

yang

dihasilkan

The vibration of the particle in the medium The vibration of the particle in the medium is

Direction of is perpendicular to the direction of the parallel to the direction of the propagation of the
vibration propagation of the wave wave
Getaran zarah dalam medium yang Getaran zarah dalam medium yang selari dengan arah
Arah gerakan berserenjang (900) dengan arah perambatan perambatan gelombang

gelombang

Water wave, Light wave and Sound wave

Example Electromagnetic wave *need a medium (air, liquid, solid) to propagate
Contoh
Gelombang air, gelombang cahaya dan Gelombang bunyi

gelombang elektromagnet *memerlukan medium (udara, cecair dan pepejal)

untuk merambat

Distance between two successive crest or Distance between two successive compression or

Wavelength trough rarefaction

Panjang Jarak di antara dua puncak atau palung yang Jarak di antara dua mampatan atau regangan yang

gelombang berturut-turut. berturut-turut.

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PHYSICAL MEANING SI UNIT SYMBOL
QUANTITY meter a
Amplitude The maximum displacement from its equilibrium position. Second T
Amplitude relates to loudness in sound and brightness in Hertz f
Period light.

Frequency The time taken for an oscillation to complete one cycle.

Wavelength T = 1
f

The number of waves produced in one second.

f = 1
T

The distance between two successive crests or two Meter l
successive troughs.

The distance between two successive compressions or
two successive rarefactions in a sound wave.

Speed of wave v = fl ms-1 v

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DISPLACEMENT-DISTANCE GRAPH

DISPLACEMENT-TIME GRAPH

To find frequency, f = 1
T

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The decrease in the amplitude of an oscillating system when its energy is drained out

as heat energy.
The amplitude of an oscillating system will gradually decrease and become zero when

the oscillation stops.
Penurunan dalam amplitud sistem berayun apabila tenaganya dialirkan sebagai tenaga
haba.
Amplitud sistem berayun akan beransur-ansur berkurangan dan menjadi sifar apabila
ayunan berhenti.

Damping
Pelembapan

Resonance occurs when a system is made to oscillate at a frequency equivalent to its
natural frequency by an external force.
The resonating system oscillates at its maximum amplitude.
Resonans berlaku apabila sistem yang dibuat untuk berayun pada frekuensi yang bersamaan
dengan frekuensi semula jadi oleh kuasa luar.
Sistem bergema berayun pada amplitud maksimum.

Resonance
Resonans

Resonance happens when,
Resonans berlaku apabila,
Driver frequency = Natural frequency
Frekuensi pemandu = Frekuensi Asli
Same length means same natural frequency
Panjang yang sama bermakna frekuensi semula jadi yang sama

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Characteristics of the REFLECTION of waves:

Physical Quantity INCIDENCE REFLECTED

Frequency WAVE WAVE

Speed Unchanged (come from the same
Wavelength
Direction of Propagation source; water wave)

Unchanged

Unchanged

Changed

Characteristics of the REFRACTION of waves:

Physical Quantity SHALLOW AREA DEEP AREA
Frequency
Velocity Unchanged (come from the same source; water wave)
Wavelength
Direction of Propagation Decrease Increase

Decrease Increase

Bends towards the normal line Bends away the normal line

Characteristics of the DIFFRACTION of waves:

Physical Quantity Condition (diffracted waves)
Frequency Unchanged (come from the same source; water wave)
Speed
Wavelength Unchanged
Amplitude (Energy) Unchanged
Decrease

LOUDNESS PITCH

Loudness increase, amplitude (energy) increase Frequency increase, pitch increase
Frequency increase, period decrease

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EXPERIMENT TO STUDY THE INTERFERENCE OF WATER WAVE

λ = ax
D

λ = wavelength of water waves

a = distance between two dippers

x = distance between two consecutive antinodal line or nodal line

D = distance between dippers and screen

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Interference of Light Waves Interference of Sound Waves

l = ax
D

The wavelength of monochromatic light can be found The wavelength of sound wave can be found by the

by the formula: formula:

a = distance between two slits a = distance between two loudspeakers
x = distance between two consecutive loud sound or soft
x = distance between two consecutive bright fringe or
dark fringe sound

D = distance between slits and screen D = distance between loudspeakers and where the
sound heard

When constructive occurs there will be a bright fringe. When constructive occurs there will be a loud sound.
When destructive occurs there will be a dark fringe. When destructive occurs there will be a soft sound.

What happens to x, when a double-slit with a bigger What happens to x, when a higher frequency is used?
separation is used?

x will decrease

λ = a ­x ¯ higher frequency, lower wavelength
D x will decrease

What happens to x, when a red laser pen is replaced λ ¯= a x ¯
by yellow laser pen? D

x will decrease
ʎ yellow < ʎ red

λ ¯= a x¯
D
State the relationship between wavelength and x. State the relationship between frequency and
ʎ decrease, x decrease wavelength.

higher frequency, lower wavelength

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The electric and magnetic field vibrate perpendicular to
each other and to the direction of propagation.

Medan elektrik dan magnet bergetar serenjang antara satu sama
lain dengan arah perambatan.

TYPE OF EM WAVE SOURCE APPLICATION
JENIS GELOMBANG SUMBER APLIKASI
ELEKTROMAGNET Electrical oscillating circuit
Radio waves Litar pemancar elektrik - Telecommunications
Gelombang Radio Telekomunikasi
l = 10-1 - 105 m Oscillating electrical charge in
a microwave transmitter - Broadcasting : tv and radio transmission
Microwave Pemancar gelombang mikro Menghantar maklumat radio dan televisyen
Gelombang Mikro
l = 10-3 – 10-1 m - Satellite transmissions
komunikasi satelit
Infrared Hot bodies, the sun and fires
Sinar Inframerah Jasad panas dan sinaran - Radar
matahari Digunakan dalam radar
l = 10-6 – 10-3 m
- Cooking
Visible light The sun, hot objects, light pemasakan makanan dengan ketuhar
Cahaya nampak bulbs, fluorescent tubes gelombang mikro
l = 10-7 m Api, jasad panas yang membara,
tiub nyahcas dan sinaran - Night vision
Ultraviolet radiation matahari Penglihatan malam
Sinar Ultraungu
l = 10-9 – 10-7 m Very hot objects, the sun, - Thermal imaging and physiotherapy
mercury vapor lamps lampu inframerah digunakan dalam
X-ray Tiub discas dan jasad yang fisioterapi
Sinar- X sangat panas
l = 10-11 – 10-9 m x-ray tubes - Remote controls
Tiub sinar-X Alat kawalan
Gamma rays
Sinar Gamma Radioactive subtances - Sight
l = 10-14 – 10-10 m Bahan radioaktif Penglihatan

- Photosynthesis in plants
proses fotosintesis

- Photography
Fotografi

- Identification of counterfeit notes
Untuk mengesan wang kertas palsu

- Sentrilisation to destroy germs
untuk pensterilan

- Radiotherapy
Radioterapi

- Detection of cracks in building
structures
Mencari retakan dalam paip logam

- Cancer treatment
Merawat kanser

- Sterilisation of equipment
Pensterilan

- Pest control in agriculture
Kawalan perosak dalam pertanian

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ELECTRICITY

CHARGE SITUATION OBSERVATION

Repel each other

or
Like charge

Unlike charge Attract each other

or A neutral object is attracted by both
Neutral object positive charge and negative charge

OHMIC CONDUCTOR NON-OHMIC CONDUCTOR
conductors which obey Ohm’s Law conductors which do not obey Ohm’s Law
E.g., a light bulb whose resistance increases over time due
to temperature increase
(heating effect of current)

Gradient is constant (resistance is constant) Gradient is increase (resistance increase)

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CHARACTERISTIC ELECTROMOTIVE FORCE POTENTIAL DIFFERENCE
Similarities
Definition Have same unit (Volt)

Symbol Can be measured by Voltmeter

Work done by a source in driving 1 C Work done in moving 1 C charge

charge in a complete circuit from 1 point in an electric field to

another point

V

E

Electrical diagram
Circuit diagram

Voltmeter reading 1.5 V (EMF) Less than 1.5 V (potential difference)
Current No current flow Current flow
(opened circuit)
Condition of the Does not light up (closed circuit)
bulb Light up
Chemical energy ® Electrical energy
Transmission of Electrical energy ® Heat energy
energy

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UNDERSTANDING & CONCEPT

1. Explain why it is more dangerous to touch the live wire of a mains supply, rather than the
SBP neutral wire.
2007 • Our bodies are at earth potential (0 V)
• If we touch the live wire, there will be a large potential difference (p.d) the live wire and our
2.
MELAKA body.
• A large current flow through it, probably fatal.
2008 • The neutral wire stays at earth potential (0 V), roughly at the same potential as our bodies.
• If we touch the neutral wire, there is no p.d. across us and so no current flows.

Diagram 11.1 shows a graph of potential difference against current for two materials, Y and
Z. One of the materials will be chosen as filament in a bulb.

3. Diagram 11.1

SBP Based on the graph in Diagram11.1, compare the resistance of materials Y and Z.
2008 Choose the more suitable material to use as a filament of the bulb. Explain your choice.

• the resistance of metal Z is constant // The resistance of metal Y is increasing
• The suitable material to be used as filament of the bulb is metal Y
• resistance increases as the temperature increases
• the higher the resistance the brighter the bulb.

Explain why the bulb connected to two dry cells lights up brighter than one bulb connected to
one dry cell. Explain.
• The two dry cells are connected in parallel
• The effective e.m.f. remains the same
• The effective internal resistance of the two cells is smaller
• A larger current will flow through the bulb to make it brighter

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4. Diagram 11.1 shows a rheostat. Rheostat is a common device used in the laboratory.

MELAKA
2009

5. Diagram 11.1

T’GANU Explain the working principle of the rheostat.
2009
• Current flows through a coil of conductor in the rheostat
• The length of wire through which by changing the position of the slider
• When the position of the slider changed, the resistance of the rheostat (Resistance) in the

circuit change
• As the result, the current in the circuit change

Diagram 12.1 shows a ping pong ball coated with thin metal foil placed between a pair of
parallel metal disc. When the E.H.T is switched on, an electric field is formed in between the
metal disc.

Diagram 12.1
Explain what will happen to the ping pong ball when it is brought to touch the metal disc
connected to positive terminal of EHT?

• Charges on the disc neutralize the negative charges on the ping pong ball
• Likes charges on the disc and the ball repelled each other
• The ball attracted by the positively charged disc
• The ball oscillates between the two plates

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6. Diagram 10.5 shows two types of plug for the electric kettle that can be connected to the electric
supply. Diagram 10.5(a) uses two pin plug, while Diagram 10.5(b) uses a three pin plug with
KELANTAN
2010 an earth wire.

Diagram 10.5

Explain why a three pin plug is more suitable compared with a two pin plug.

• Two pin plug has no earth wire // three pin plug has earth wire

• using 2 pin plug, if there is leakage of current it will also flow through the metal body // using
3 pin plug if there is leakage of current it will flow to the ground

• The person who touches the metal body will experiences electric shock // using 3 pin plug,
the current will be earthed

• using 2 pin is not safe to the consumer // Using 3 pin plug is more safer to the consumer

7. Explain the advantages of parallel circuit in a house wiring system.

PAHANG • A parallel circuit can run several devices using the full voltage of the supply.
2010 • If one device fails, the others will continue running normally
• If the device shorts, the other devices will receive no voltage, preventing overload damage.
8. • A failure of one component does not lead to the failure of the other components.
SBP • More components may be added in parallel without the need for more voltage.
2014 • Each electrical appliance in the circuit has its own switch.

Batteries with internal resistance connected in series and in parallel as shown in Diagram 10.3
will affect the brightness of the bulbs. Explain why.

Diagram 10.3

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9. • Bulb is brighter using 4 batteries in parallel.
• 4 batteries in parallel has the same emf as 2 batteries in series.
MRSM • Internal resistance for batteries in parallel is less
2016 • Current flow is higher when 4 batteries are connected parallel.

Diagram 12.1 shows a new packet of batteries with information about its characteristics.

Diagram 12.1

With the aid of a circuit diagram and a graph, explain how internal resistance of a battery can
be determined.

• All apparatus are connected correctly
• all apparatus are correct

• correct graph
• The internal resistance is determine from the gradient of the graph.

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10. Diagram 12.3 shows the graph of the relationship between the potential difference and the
current of a constantan wire and a filament bulb.
GERIK
2018

Diagram 12.3

Describe the graph of the potential difference graph against current for constantan wire and
filament bulb. In your description, explain in terms of resistance and temperature.

• Filament bulbs: Gradient graph increases
• resistance increases when temperature increases
• Constantans wire: gradient constant
• temperatures increases resistance constant

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ELECTRONIC

MAIN PART COMPONENT FUNCTION
Filament When a current passes through the filament, the filament becomes
hot and heats up the cathode.
Electron Cathode Emits electrons when it is hot.
gun Control Grid
à Control the number of electrons hitting the fluorescent screen.
Focusing Anode à Control the brightness of the spot on the screen.
To focus the electrons onto the screen

Deflecting Accelerating Anode To accelerate the electrons to high speed.
system Y-Plates To deflect the electron beam vertically.

X-Plates To deflect the electron beam horizontally

Fluorescent Glass surface coated To convert the kinetic energy of the electrons to heat and light

screen with a fluorescent energy when the electrons hit the screen.
material

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Graph and calculation involving CRO
Waveform by CRO

y-input Time base is off Time base is on

No input

Dry cell
(d.c current)

a.c power supply
(from voltage
regulator)

EXAMPLE:
Diagram 3 shows a trace on an oscilloscope for an a.c. source. The y-gain is set to 1.5 V cm-1 and the time
base is 2 ms cm-1.

Diagram 3

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(a) Calculate the Vp, Vpp and Vrms.

Peak voltage Peak-to-peak voltage Root mean square voltage

Vp Vpp !& Vrms
Vp = 1.5Vcm-1 × 2divs Vpp = 1.5Vcm-1 × 4divs √(
Vrms =
= 3.0 V = 6.0 V
= ).+
√(
= 2.12 V

(b) Calculate the time taken for one waveform.
Time for one wave, T = 2 ms cm-1 × 4 divs

= 8 ms
= 8 × 10-3 s

(c) Calculate the frequency, f of the a.c source.
, ,
Frequency, f = # = (.×,+01)

= 125 Hz

(d) Sketch the trace that will be displayed if the setting are changed to
(i) 1 V cm-1 and 2 ms cm-1

(ii) 1 V cm-1 and 1 ms cm-1
(iii) 3 V cm-1 and 2 ms cm-1

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(iv) 3 V cm-1 and 1 ms cm-1
(v) 1.5 V cm-1 and 4 ms cm-1

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N-Type AND P-Type SEMICONDUCTOR

CHARACTERISTIC P-Type SEMICONDUCTOR N-Type SEMICONDUCTOR
Doping Material TRIVALENT: PENTAVALENT:

Aluminum, Boron, Indium and Gallium Antimony, Arsenic and Phosphorus

(BAGI) (APA)

Role of doping Atom receiver Atom donor
material Holes Free electrons

Majority Charge Free electrons Holes
Carrier

Minority Charge
Carrier

SEMICONDUCTOR DIODE

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FORWARD BIAS REVERSE BIAS

• The cell voltage greater than the junction • The cell voltage is lower than the junction
voltage. voltage.

• The depletion layer is narrow, and the • The depletion layer is wide, and the

resistance of diode decreases. resistance of diode increases.

• Hence a large current flows through the • Hence only a very small current (leakage

diode. current) flows through the diode.

• Bulb light up. • Bulb not light up.

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Ø HALF-WAVE RECTIFICATION

• The current will only flow in the first half-cycle when the diode in forward bias.
• The current is blocked in the second half-cycle when the diode is in reverse bias.

Ø FULL-WAVE RECTIFICATION

• In the first half, the current flows from P → B → D → Q.
• In the second half, the current flows from Q → C → A → P.

Ø THE USES OF CAPASITOR

1. When the current pass through the resistor and capacitor, the capacitor is charged and stores
energy.

2. When there is no current pass through the resistor and capacitor, the capacitor discharge and
the energy from it is used to produce voltage across the resistor.

3. As a result it produces a smooth dc output.

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Transistor as an automatic switch

Diagram 13

Light Dependent Resistor (LDR) has a very low resistance when exposed to sunlight but very high
resistance when at nighttime.

Again to remember:
High resistance® Cause high potential difference

The arrangement of R1 resistor and LDR along AB is used as potential divider of the voltage.
3" 563
Voltage at R1 = (3"4563) × 12 V and Voltage at LDR = (3"4563) × 12 V

Function of base resistor is to control the base current.

Function of transistor in this circuit is as an automatic switch.

Þ Explain the working principle of transistor circuit in daylight.

1st: In daylight, the LDR has very low resistance as exposed to sunlight.
2nd: Low resistance of LDR will cause a smaller share of battery voltage across it.
3rd: This low voltage across the base-emitter does not switch the transistor on.
4th: Therefore, the transistor circuit is not complete and the lamp does not light up.

Þ Explain the working principle of transistor circuit in nightime.

1st: In nightime, the LDR has very high resistance as the surrounding is dark.
2nd: High resistance of LDR will cause a high share of battery voltage across it.
3rd: This high voltage across the LDR will drive a base current through the

transistor and switch it on.
4th: Therefore, the transistor circuit is complete and the lamp lights up.

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Transistor as current amplifier

X Loudspeaker

R Capacitor 40 kΩ C P
Microphone E 6 V dc
B Q
Y

10 kΩ

SZ

Diagram 14

1st: The microphone is to convert the sound energy into electrical energy. This
electrical energy will be sent to capacity.

2nd: The capacitor will block the steady current and allow the a.c current to pass
through it.

3rd: The small a.c current will pass to the base of transistor will cause a big
amplification to the output current.
Here, the transistor is act as current amplifier.

4th: The loudspeaker now converts the electrical signal back to sound energy again.

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THE USES OF TRANSISTOR

LIGHT CONTROLLED SWITCH

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Logic gates are the decision makers in electronic systems.

They are called gates because they can have many inputs to a device but only give a single
output.

GATES SYMBOL BOOLEAN TRUTH TABLE
EXPRESSION

AND X=A•B INPUT OUTPUT
gate AB X
00 0
01 0
10 0
11 1

INPUT OUTPUT

X = A +B AB X

OR 00 0
gate 01 1
10 1

11 1

NOT NOT gate is different from X=A INPUT OUTPUT
gate other logic gate as it has only A X
0 1
one input with one output. 1 0

NAND X=A •B INPUT OUTPUT
gate AB X
00 1
01 1
10 1
11 0

NOR INPUT OUTPUT
gate AB X
00 1
X=A +B 01 0
10 0
11 0

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X-OR X = A ÅB INPUT OUTPUT
gate AB X
X= AÅB 00 0
X-NOR 01 1
gate 10 1
11 0

INPUT OUTPUT
AB X
00 1
01 0
10 0
11 1

Electric circuit which represents the logic gates Electric circuit
Logic Gate

AND Gate
Both inputs must be closed to complete the circuit

OR Gate Either one switch or both are closed will complete the circuit

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NOT Gate
Input 1 is closed will cause the bulb to switch off. Input 1 acts as current jumper

NAND Gate
Both inputs closed will switch of the bulb.
(Current jumper occurs when both the inputs are closed)

NOR Gate
Either one or both inputs closed will switch off the bulb

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Radioactivity

Ø CHARACTERISTICS OF THE THREE TYPES OF RADIOACTIVE EMISSIONS

Radioactive Alpha particles Beta particles Gamma rays
emissions
24a b0 g
Symbol
Positive charged , helium -1 Neutral electromagnet ray
Nature nucleus He Electron
Charge 0
Speed +2 electric charges -1 electric charge
Speed of light
Energy (1/20 ) x the speed of light, cc 3 % - 99 % of the speed of
In an electric light , c Nil
For a particular source, all α
field particle are emitted with the For a particular source β- Does not bend , showing
particle emitted have various that it is neutral
In magnetic field same KE
Bends to negative plate KE Does not bend showing
Ionising power Bends to positive plate that it is neutral.
Penetrating Bends a little showing that it has
power a big mass. Direction of the Bend a lot showing that it Weakest
Stopped by has a small mass. Direction High
Range in air bend indicates that it is positively of the bend indicates that it
charges A few centimeters of lead
Strongest is positively charged or concrete
Low Intermediate
Intermediate A few hundred metres
A thin sheet of paper
A few millimeters of
A few centimetres aluminium

A few metres

Ø RADIOACTIVE DETECTORS RADIACTIVE EMISSION
Alpha particles Beta particles Gamma rays
DECTECTOR
√√
Photographic Films
Gold Leaf Electroscopes √√
Cloud Chambers
Geiger – Muller Tube (G.M Tube) √ √√

√ √√

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Ø CHANGES IN THE PROTON NUMBER AND NUCLEON NUMBER IN
RADIOACTIVE DECAY

ALPHA DECAY BETA DECAY GAMMA EMISSION

EQUATION A X ® YA-4 + 24He A X ® Z +A1Y + -10e A X ® A X + g
Z Z Z Z
Z -2

210 Po ® 206 Pb + 4 He 239 Pa ® U239 + -10e 210 Po ® 28026 Pb + 4 He + g
84 82 2 91 84 2
92

EXAMPLE U238 ® 23940Th + 4 He 164C ® 14 N + -10e 2670Co ® 2670Co + g
2 7
92

Radioisotopes is unstable isotopes which emit radioactive rays // unstable isotopes which decay
which emit radioactive rays

APPLICATIONS OF RADIOISOTOPES:

USE IN RADIOISOTOPE USES
SOURCE
- to treat an overactive thyroid gland
1. Sodium iodide and thyroid cancer

MEDICINE 2. Sodium-24 - to detect the position of blood clot
3. Phosphorus - to detect and treat brain tumor

4. Cobalt-60 - to destroy cancer cell
- to sterilize medical equipment

1. Sodium-24 - to detect leakage of underground pipes

INDUSTRIES 2. Polonium-210 - neutralize static charge in
photographic plates and other
material

AGRICULTURE Nitrogen-15 & Phosphorus-32 - as tracer in the study of the effectiveness of
ARCHEOLOGY Carbon-14 fertilizers

- to determine the age of artifacts
(carbon dating)

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DEFINITION NUCLEAR FUSION NUCLEAR FISSION
A process the combining of two lighter A process of splitting a heavier nucleus into two
PROCESS THAT nuclei to form a heavier nucleus, releasing lighter nuclei and emitting several neutron and
TAKES PLACE a vast amount of energy during the energy.
process.
CAN THE RATE Light nuclei at high speeds and very high Moving particles, e.g. neutrons, hit and break up
OF REACTION BE temperature overcome the repulsion force heavy nucleus and produce enough neutrons to
and fuse to form a single nucleus break up other nuclei (chain reaction)
CONTROLLED?
EXAMPLES Difficult to control Can be control

Fusion is the process that powers the Sun Fission is the process in a nuclear reactor

EQUATION 2 H + 13H ® 24He + 10n
1

DIAGRAM

Chain Reactions is a self – sustaining reaction in which the products of a reaction can initiate another
similar reaction.

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ADVANTAGES OF USING DISADVANTAGES OF USING
NUCLEAR FISSION NUCLEAR FISSION

§ Nuclear power costs about the same as coal, so § The initial cost to design and build a nuclear
it is not expensive. power station is very high.

§ It does not produce smoke or carbon dioxide. § There is always a risk of accidents. If a chain
It does not contribute to the greenhouse effect. reaction goes out of control, explosion or leakage
It produces less waste than fossil fuels. or large amounts of radioactive substance may
happen.
§ It produces huge amounts of energy from small
§ Used fuel rods are very hot and highly radioactive
amounts of fuel. with very long half-lives.
§ Nuclear power stations need less fuel than
§ Expensive procedures are required to cool down
stations which use fossil fuels. the rods and store them.
§ Vast reserves of nuclear fuel in the world.
§ Safety procedures in the administration of § The hot water discharged from the nuclear power
stations can cause thermal pollution.
nuclear reactors are very advanced and safe.
§ Produces useful radioisotopes as by-products § People who work in the nuclear power station and
those living nearby may be exposed to excessive
that can be used in industry, medicine, radiation.
agriculture and research.

A NUCLEAR REACTOR

PART OF REACTOR FUNCTION
It produces tremendous amount of energy through nuclear fission.
URANIUM FUEL RODS The nuclei are split by neutrons in a controlled chain reaction,
releasing a large amount of energy. The energy released heats up the
GRAPHITE cold gas that passes through the reactor core.
MODERATOR
Acts as a moderator to slow down the fast neutrons produced by the
BORON OR CADMIUM fission.
CONTROL ROD Slower neutrons are more readily captured by the uranium nuclei.
CONCRETE SHIELD The boron control rods absorb neutrons. It can control the rate of
COOLANT fission reaction. When rods are lowered into the reactor core to absorb
HEAT EXCHANGER some of the neutrons, the rate of the fission reaction reduced.
TURBINES Prevents leakage of radiation from the reactor core.
COIL AND
MAGNET Take away the heat from the nuclear reactor. Substances with high
specific heat capacity such as water and carbon dioxide are used.
Heat energy from the very hot gas is used to boil the water into steam
The turbines are rotated by the flow of steam under high pressure
The coils are rotated by the turbines. Electricity is generated by
electromagnetic induction.

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REALISING THE IMPORTANCE OF PROPER MANAGEMENT OF RADIOACTIVE
SUBSTANCES

SOMATIC EFFECT Ø Somatic effect appears in the person exposed to radiation. The seriousness of
GENETIC EFFECT the damage depends on the dose of radiation received.

Ø Fatigue, nausea, hair loss, radiation burns, cataracts, Blood disorder
(leukaemia), organ failure, death.

Ø Genetic effect affects the reproductive cells and can lead to defective offspring in
the future generations of the exposed person.

Ø Birth defects, congenital defects, premature death, chromosome abnormalities,
cancer in later life.

Safety precautions needed in the handling of radioactive substances:

Ø Read and follow the advice and instructions marked on radioactive sources, equipment and work
manuals.

Ø Gloves must be worn any time an unsealed source is being used or whenever contamination is
likely to occur.

Ø Laboratory coats, long pants, and closed-toe footwear should be worn.
Ø Eating, drinking, applying cosmetic or storing food is prohibited.
Ø All work surfaces and storage areas should be covered with absorbent material to contain

radioactive material contamination.
Ø When using radioactive liquids, plastic or metal trays (stainless steel washes easily) should be

utilized to contain potential spills.
Ø Radioactive material, especially liquids, should be kept in unbreakable containers whenever

possible. If glass is used, a secondary container is necessary.
Ø Before eating or drinking, wash hands and forearms thoroughly.
Ø Stronger radioactive sources should be handled with robotic control systems behind steel,

concrete, lead or thick glass panels.
Ø Radiation badges containing photographic film should be worn to monitor exposure to radiation.

The film is regularly developed. The darkness of the film shows the level of exposure to radiation.

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QUESTION:

X, Y and Z are three different radioactive substances.
X emits only α-particles, Y emits only β-particles and Z emits only γ-rays.
You are required to carry out investigation to identify the types of radiation by using
Geiger-Muller tube.
- Draw a diagram to show how you carry out the investigation.
- Describe the procedures and explain how you arrived at the conclusion

ANSWER:

PROCEDURES
• Observed the reading on the scale without an absorber
• Put a piece of paper, aluminium and lead between the source and the
detector in turns
• For each kind absorber, record the reading on the rate meter
• Carry out the same procedure for the three substances
• α radiation will be stopped by all three kinds of absorber
• β radiation will be stopped by aluminium and lead
• γ will be stopped by lead only

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QUESTION:

Sketch activity against time graph to show the decay of a radioactive substance.
Explain how the half-life is determined.

ANSWER:

N = Amount of radioisotope particles after nth half-life
No = Initial amount of radioisotope particles

NUCLEAR REACTOR

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