Reading in Science

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Static Electricity Lesson 6

thundercloud path static
rods bottom particles
charges light bulbs positive

Fill in the blanks.

A buildup of electrical charge causes electricity.

This discharge of static electricity can produce lightning from a

huge cloud called a(n) . One hundred million

can be powered by just one bolt. Lightning takes

the shortest, clearest to the ground. That’s why

people use lightning to discharge lightning into the

ground. Inside thunderclouds, water and ice rub

together. At the top of the cloud, lightweight ice

particles gather together. Heavy, negative water particles settle at the

of the cloud. The ground stays positive relative © Macmillan / McGraw - Hill

to the clouds. Soon, with enough build up of ,

lightning results.

336 Unit F · Energy Use with textbook pages F68–F75

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Current Electricity Lesson 7

Fill in the blanks. Reading Skill: Cause and Effect - questions 8, 12, 13,
19, 20

How Does Electricity Flow?

1. In order to flow, electricity must follow a(n) .

2. The complete path that electricity can move through is called a(n)
.

3. The electricity that flows through a circuit is called .

4. Current electricity is different from , which does
not flow.

5. Current electricity will flow only through a(n) circuit.

6. If there are gaps or breaks in a path, it is called a(n)
circuit, and no electricity will flow.

7. A device called a(n) controls the flow of current in
a circuit.

8. When a switch is in the closed position, the circuit is ,
.
the path is , and current

9. The strength of an electrical current is measured in .

What Affects the Flow of Electricity?

© Macmillan / McGraw - Hill 10. Current does not flow easily through a poor conductor, which is also

known as a(n) .

11. Resistors allow electrical energy to be changed to other forms
of .

12. Because the of a light bulb is a resistor, it allows

the light bulb to change electrical energy to and

.

Unit F · Energy Use with textbook pages F76–F85 337

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13. When too much current flows through a wire, it Lesson 7

can cause a .

Where Does Current Come From?

14. One way to make current is to use a(n) , which
changes chemical energy into electrical energy.

15. A(n) is made up of several connected cells.

What Kinds of Circuits Are There?

16. A circuit that has two objects connected in a single path is a(n
circuit.

17. A circuit that connects each object to the cell separately is a(n)
circuit.

How Can Circuits in Homes Be Protected?

18. Short circuits are dangerous because and
a. .
b.

19. When dangerously high current flows through a(n) ,
a thin strip of metal melts, which creates an open circuit and current ,
stops flowing.
© Macmillan / McGraw - Hill
20. When dangerously high current flows through a(n)
overheated metal pushes the switch open to create an open circuit.

21. A circuit breaker in the off position should not be pushed to the on

position until the problem is .

338 Unit F · Energy Use with textbook pages F76–F85

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How Does Electricity Flow? Lesson 7

The picture below shows a circuit. The labels and pointers show objects in
the path of the circuit. Look at the picture and follow the path of the
electricity.

Light bulb

D-cell

Cell holder Filament
Glass cover
Switch Support wires
Glass mount
Use the picture to answer the questions. Insulation
1. List the objects in the path of the circuit.
Screw thread contact

Electrical foot contact

2. What does the caption tell you about why this circuit is closed?

3. What does the switch do?

© Macmillan / McGraw - Hill 4. There is a coiled wire on top of a light bulb that gets heat when energy
is turned on. What is the name of that part?

5. What do you think would happen if there was a gap or break in the
circuit?

Unit F · Energy Use with textbook page F78 339

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What Kind of Circuits Are There? Lesson 7

Circuits can be connected in different ways. A series circuit has two objects
connected in a single path. A parallel circuit has two objects connected with
two separate paths. The arrows in each diagram show how the current flows
through the parts of the circuit.

D-cell Series D-cell Parallel – +
–+
Wire
Wire

Connection Series Parallel
Both bulbs are on Each bulb is on a
Removing the same circuit. separate circuit.
one bulb Both bulbs Only the removed
Brightness go off. bulb goes off.
Dim Bright

Answer these questions about the diagrams above.
1. What type of connection does a parallel circuit have?

2. What happens when you remove one bulb from a series circuit? © Macmillan / McGraw - Hill

3. Which of the circuits gives off the brightest light?

340 Unit F · Energy Use with textbook pages F82–F83

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Current Electricity Lesson 7

Fill in the blanks.

1. The path that electricity can move through is called current
a. electricity
fuse
2. Moving electrical charge is known as series circuit
. parallel circuit

3. A circuit arrangement that has two objects con-

nected in a single path is a .

4. When each object is connected to a cell separately, circuit breaker
the arrangement is known as a circuit
.

5. A device with a thin metal strip that melts upon contact with too much

current and causes an open circuit is called a .

6. A switch that protects circuits by creating an open circuit when current is

too high is called a .

Answer each question.

7. What should an adult do if electrical devices stop working in a
newer home?

© Macmillan / McGraw - Hill 8. What is the difference between an open circuit and a short circuit?

Unit F · Energy Use with textbook pages F76–F85 341

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Current Electricity Lesson 7

fuses open circuit circuit breakers
short circuit circuit closed circuit
current electricity switch

Fill in the blanks.

Think about how a model train set and electricity are alike. A complete

set of tracks for the train is like a complete path for the electricity. The

complete path for electricity is called a(n) . There are

no gaps or breaks in a(n) . The model train moves

because it has electric energy. It is like which also

moves because it has energy. If the train tracks get a gap in them, the

train does not move. In a similar way, current cannot flow in a(n)

. Model trains often have a(n)

to control the flow of energy. Electric and

protect against the flow of too much current. Too © Macmillan / McGraw - Hill

much current is called a(n) , and can be dangerous.

342 Unit F · Energy Use with textbook pages F76–F85

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Electricity and Magnets Lesson 8

Fill in the blanks. Reading Skill: Cause and Effect - questions 7, 9, 22

What Is a Magnet?

1. Rocks called contain magnetized iron.

2. A material or device that attracts items containing the elements iron,

nickel, or cobalt is a(n) .

3. Every magnet has two ends, or .

4. The pull of a magnet is at its poles.

5. Like poles of a magnet , while unlike poles
.

6. The needle of a(n) turns toward Earth’s North Pole.

7. Hanging magnets line up in a north-south direction because
itself is a magnet.

8. A region of magnetic force is called a(n) .

What Is an Electromagnet?

9. A weak magnetic field is produced when a runs in a
wire.

10. A temporary magnet created when current flows through wire wrapped

© Macmillan / McGraw - Hill in loops around an iron bar is called a(n) .

11. Electromagnets are used:

a. ,
b. , and
c. .

Unit F · Energy Use with textbook pages F88–F99 343

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How Is Electricity Made? Lesson 8

12. Two-way current is called , or AC.

13. A device that produces alternating current is called a(n)
.

14. Current produced by dry cells, such as cells and batteries, flows in only

one direction and is known as .

15. A(n) is an outside source that spins the coil in
a generator.

16. Sources of power for a turbine are ,
, and .

How Does Current Get to Your Home?

17. Current travels from a power plant to a(n) that

increases voltage, through to a second transformer

that voltage, and into your home.

18. A measure of force with which negative charges flow is called
.

How Can You Use Electricity Safely?

19. If you touch a walk socket with anything other than a plug, it could

cause current to flow from the socket to the to

.

20. If you overload a plug with too many devices, it could cause the plug to © Macmillan / McGraw - Hill

, heat up, and start a(n) .

344 Unit F · Energy Use with textbook pages F88–F99

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What Is a Magnet? Lesson 8

Look at the way the particles line up in the top illustration. Think about why
one is magnetic and one is not. Then look at the photographs of magnets
below. How are the two photographs different?

Magnetized iron Nonmagnetized iron

NS

Electr

© Macmillan / McGraw - Hill Fill in the blanks. .
1. What do a south and a north pole do to each other?

2. What do the south poles do to each other?

3. In magnetized iron, the particles are
.

4. In nonmagnetized iron, the particles are

Unit F · Energy Use with textbook pages F90–F91 345

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How Is Electricity Made? Lesson 8

Look at the diagrams of a generator. A generator is a device that produces
alternating current. Notice what happens when the current is flowing, not
flowing, and flows in the opposite direction.

How Generators Work

An outside force spins the When no part of the coil As the coil continues to
coil between the poles of is actually passing spin, the side now passes
a powerful magnet. through the magnetic down through the field.
Current flows as one side field, no current flows. Current once again flows,
of the coil passes through but in the opposite
the magnetic field. direction.

Answer these questions about the pictures above.
1. What happens to the current if an outside force spins the coil?

2. What happens to the current when no part of the coil is passing through © Macmillan / McGraw - Hill
the magnetic field?

3. What happens to the current as the coil continues to spin?

346 Unit F · Energy Use with textbook page F94

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Electricity and Magnets Lesson 8

Fill in the blanks.

1. Each end of a magnet is called a(n) generator
. magnetic field
direct current
2. A region of magnetic force is known as a(n) pole
. electromagnet

3. When current flows through wire wrapped in coils .

around a bar magnet, a temporary magnet known

as a (n) is created.

4. A current that flows only in one direction is a(n)

5. Alternating current is produced by a device called a(n)
.

Answer each question.

6. What are some sources that spin the coil of a turbine, therefore causing
generators to work?

7. Why is it necessary to know how to use electricity safely?

© Macmillan / McGraw - Hill

Unit F · Energy Use with textbook pages F88–F99 347

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Electricity and Magnets Lesson 8

transformer poles generator
outside forces voltage magnetic field
alternating current

Fill in the blanks.

The kind of electricity that comes into our homes is called

. A device called a

creates this type of current. To make the current, a coil spins between the

of a powerful magnet. The coil spins from

such as steam, wind, moving water, or nuclear

power. Current flows as one side of the coil passes up through an area of

magnetic force, or . The coil continues to spin. The

side of the coil then passes down through the field instead of up. Current

flows in the opposite direction. Current with high

cannot be used in a home because it is dangerous. The current then © Macmillan / McGraw - Hill

travels to a , which decreases the voltage. The

electricity then enters your home.

348 Unit F · Energy Use with textbook pages F88–F99

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Electricity and Magnetism Chapter 13

Circle the letter of the best answer.

1. A buildup of electrical charge is called

a. current electricity. b. negative charge.

c. static electricity. d. positive charge.

2. A material through which electricity flows easily is called a(n)

a. conductor. b. insulator.

c. producer. d. resistor.

3. When a buildup of electrical charge moves onto another object, it is called

a. voltage. b. vibration.

c. conduction. d. discharge.

4. A material through which electricity does not flow is called a(n)

a. circuit. b. insulator.

c. magnet. d. conductor.

5. A complete path that electricity can move through is a(n)

a. ampere. b. circuit.

c. resistor. d. current.

6. A moving electrical charge is known as

a. switch box. b. path of flow.

© Macmillan / McGraw - Hill c. current electricity. d. static electricity.

7. A type of circuit in which two objects are connected by one path is a(n)

a. series circuit. b. open circuit.

c. closed circuit. d. parallel circuit.

Unit F · Energy Use with textbook pages F66–F101 349

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Circle the letter of the best answer. Chapter 13

8. A type of circuit in which each object is connected

separately to the cell is a

a. dry cell. b. short circuit.

c. bar magnet. d. parallel circuit.

9. A device that keeps too much electrical current from flowing through

wires is called a

a. circuit. b. magnet.

c. fuse. d. flashlight.

10. A switch that protects circuits is called a

a. dry cell. b. power plant.

c. circuit breaker. d. series circuit.

11. The place where a magnet’s pull is the strongest, one of two ends, is

called a(n)

a. cell. b. pole.

c. compass. d. current.

12. A region of magnetic force around a magnet is known as a

a. bar magnet. b. hanging magnet.

c. South pole. d. magnetic field.

13. A temporary magnet created when current flows through wire wrapped © Macmillan / McGraw - Hill

in coils around an iron bar is a(n)

a. electromagnet. b. magnetite.

c. generator. d. cell.

14. Alternating current is produced by a device known as a(n)

a. turbine. b. generator.

c. coil. d. battery.

350 Unit F · Energy Use with textbook pages F66–F101

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Name That Word Unit F

Read each description, then write the word or words being described. Use
the Word Box to check your spelling.

Word Box

force speed load insulator heat
static electricity pitch pole
magnetic field efficiency

1. A material that electricity doesn’t easily flow through.

2. These words identify a buildup of an electric charge.

© Macmillan / McGraw - Hill 3. An area of magnetic force.
4. The highness or lowness of sound.
5. One of two ends of a magnet, where the magnet’s pull is the

strongest.
6. The object being moved by a simple machine.
7. The distance an object moves in a certain amount of time.

8. The flow of energy from one material to another.
9. Each push or pull.
10. The measure of how much useful work a machine puts out compared to

the amount of work put into it.

Unit F · Energy Use with textbook pages F2–F104 351

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Correct-a-Word Unit F

One word in each sentence below is wrong.

Cross it out and write the correct word above it. Use the Word Box to check
your spelling.

conductor circuit inertia terminal resistor
radiates convection vibrations electromagnet spectrum

resistor © Macmillan / McGraw - Hill
1. Electricity has difficulty flowing through a resistan.

2. One example of conviction is heating a liquid in a pot.

3. Wires can be attached to a turnminel on a battery.

4. Scientists call the seven colors of light that make up white light the
visible spacdrum.

5. The Sun’s energy radishes through space.

6. An electricmagnet is made when current flows through wire wrapped
around an iron bar.

7. Inerita is the tendency of an object to stay in motion or at rest until a
force acts upon it.

8. A circus is a complete path electricity can flow through.

9. Electricity flows easily through a condoctor.

10. Violets make the sounds you hear coming from guitars.

352 Unit F · Energy Use with textbook pages F2–F104

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FIND-A-WORD Unit F

Look across, down, and diagonally to find these hidden words:

CHARGE, CIRCUIT, COIL, CONDUCTOR, CURRENT, DRY CELL,
ELECTRICITY, ELECTRODE, ELECTROMAGNET, ENERGY, FIELD,
FORCE, FUSE, GENERATOR, PLUG, POLE, POWER, PULL, PUSH,
RADIATE, RESISTOR, RESOURCE, SOLAR, STATIC, SWITCH, TERMINAL,
TRANSFORMER, TURN, VOLT, WOOD.

© Macmillan / McGraw - Hill G CH A R GEV X R T UR N
E E L E C T ROMA G N E T
L Z N Q J POL E D F P S E
E F I E L DQ T C I O U O R
C C U R R ENT OA R S UM
T E I S Z ASW I T C H R I
R NZ R E ZTO L E E XC N
I E L E C TROD E Q Z E A
C R X P L UGD R Y C E L L
I G S T A T I C E P O WE R
T YR E S I STOR P UL L
Y T R A N S FO RME RQ Z
C ON D U CTO R S O L A R

Unit F · Energy Use with textbook pages F2–F104 353