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ELECTRICAL CURRENT

Electric current is the flow1 of electric charge2. It

transmits energy called electricity.

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ELECTRICITY

Electricity is the flow of electrical power or charge. It is a

secondary energy source which means that we get it from the

conversion of other sources of energy, like coal, natural gas, oil,

nuclear power and other natural sources, which are called

primary sources. The energy sources we use to make

electricity can be renewable or non-renewable, but

electricity itself is neither renewable or non-renewable.

Electricity is a basic part of nature and it is one of our most widely3 used forms of

energy.

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1 Flow: the continuous movement of something in one direction 2 Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. 3 Widely:

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ELECTRICITY PRODUCTION

Electricity is produced at power stations or power plants.

Water, steam4 or wind moves a turbine connected

to a generator. When the turbine rotates, the

generator converts mechanical energy into

electricity, using a magnetic field and a conductor.

Power stations use different energy sources to move

the turbine. Some use non-renewable energies, such

as coal, while others use renewable energies, such as

wind.

ELECTRICITY TRANSMISSION

The electricity generated at a power station is transmitted through

conducting wires to substations near populated areas. It is

transmitted through tall towers and special electrical power lines

called high-tension power transmission lines.

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4 Steam: the hot wet substance like a cloud that is produced when water is heated.

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ELECTRICITY DISTRIBUTION AND CONSUMPTION

Power lines distribute electricity to homes, offices and industries. It is used by different

appliances to produce:

Heat: radiators

Movement: washing machines

Light: computers

Sound: doorbells

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HEAT LIGHT MOVEMENT SOUND

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ELECTRIC CIRCUITS

An electric circuit consists of different components connected to each other to allow

the flow of an electrical current.

The four basic components of an electric circuit are:

1. A generator. Which is the source of electricity, such as an electrical plant or a

battery.

2. An electrical component, such as a light bulb or a motor.

3. Conducting wires.

A switch to control the flow of electrical current. A switch in the position closes the

circuit and allows the flow of electrical current. A switch in the off position opens the

cir

There are 2 kinds of circuits and conductors:

1. Electrical conductors

• Some materials let electricity pass through

them easily. These materials are known as

electrical conductors.

• Many metals such as aluminium, copper, iron

and steel, are good electrical pass through are

always made of metal.

2. Electrical insulators

• Some materials do not allow electricity to pass

through them. These materials are known as

electrical insulators.

• Plastic, wood, glass and rubber are good electrical

insulators. That is why these materials are often

used to cover materials that carry electricity.

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TYPES OF CIRCUITS

Series Connections Parallel Connections

VOCABULARY

Match:

a. The flow of electrical charges . . insulators

a. Electrical current flows easily through these materials . . electrical current

b. Electrical current does not flow easily through these materials . . a switch

c. The source of electricity in an electric circuit . . conductors

e. It controls the flow of electrical current in an electric circuit . . a generator

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Activities:

1. Complete the sentences.

Repel neutral negatively attract positively

a) If an object has more negative charges than positive charges, it is ___________

charged.

b) If an object has more positive charges than negative charges, it is ____________

charged.

c) If an object has the same number of positive and negative charges, it is

__________.

d) Objects with the same charges ________________________ each other.

e) Objects with opposite charges ________________________ each other.

2. Write true or false

True False

1 A magnet is an object that can attract all types of objects

2 Magnets have two poles

3 Opposite magnetic poles repel each other

4 To make an electromagnet, you only need a conducting wire

5 Magnetic strips store information on credit cards

3. What does electricity produce in each case (heat, movement, light or sound)?

Heat Movement Light Sound

Lights on

Electric razor

Radio

Hair dryer

Radiator

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INVESTIGATION

1. What happens if you remove one of the light bulbs from the series circuit?

2. What happens if you remove one of the light bulbs grom the parallel circuit?

3. How is a string of lights for a Christmas tree connected, in series or in parallel?

Why?

4. Match and complete the table

Electricity is a form of energy that lights our towns, heats our homes and moves

machines. Primary energy sources like coal, natural gas, oil, nuclear power, wind, water

and the sun produce electricity. Electricity is a secondary energy source. We use

electricity every day.

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5.

6.

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MAGNETS

A magnet is an object which can attract objects made of iron, such as steel. This

attraction is called magnetism.

Magnets can be naturals, such as a mineral magnetite, or artificial,

such as magnets manufactured from metal.

Magnets have two poles: north and south.

When the opposite poles of two magnets are placed

together, the magnets attract each other. If the same

poles are placed together, the magnets repel each other.

MAGNETIC FIELDS

Magnets create magnetic fields. They are the space around a

magnet, where materials, such as iron filings, are affected by

magnetic forces.

ELECTROMAGNETS

An electromagnet is a conducting wire wrapped around a piece of

iron, called a coil, which acts as a magnet when electrical current

flows thought it.

MAGNETITE

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THE USES OF MAGNETS

Magnets are used in electric motors and generators for telephones, lights, televisions,

computers and more.

• Magnetic recording media are used in audio cassettes, floppy disks and hard

disks to store information in a very small space.

• Magnetic strips store information on credit cards.

• Electromagnets are used in televisions, computer monitors, loudspeakers and

microphones.

magnetic recording media magnetic strips electromagnets

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Activities:

1. Match and write.

This force slows or stops moving objects . .gravity

This force affects magnets and some metallic objects . . magnetic force

This force makes objects fall to the ground . . friction

This force is found in objects with electrical charges . . electric force