Electricity and Magnetism

1) What is the main difference between how a permanent magnet and an electromagnet can be used?

• A permanent magnet can be turned on and off, while an electromagnet cannot.

• An electromagnet can be turned on and off, while a permanent magnet cannot.

• Both can be turned on and off.

• Neither can be turned on and off.

Answer explanation

An electromagnet can be turned on and off by controlling the electric current, while a permanent magnet maintains a constant magnetic field and cannot be switched off.

2) Which electromagnet would make more magnetism?

• Electromagnet with more turns of wire

• Electromagnet with fewer turns of wire

• Electromagnet with a weaker current

• Electromagnet with a stronger current

Answer explanation

An electromagnet with more turns of wire generates a stronger magnetic field due to the increased number of loops, which enhances the magnetic effect. Therefore, it makes more magnetism compared to fewer turns.

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4) What kind of energy change does an electric motor perform?

• Electrical energy to mechanical energy

• Mechanical energy to electrical energy

• Chemical energy to electrical energy

• Thermal energy to mechanical energy

Answer explanation

An electric motor converts electrical energy into mechanical energy, allowing it to perform work, such as turning a fan or driving a machine. This is why the correct answer is 'Electrical energy to mechanical energy'.

6) What would you expect to happen to an electric motor as the amount of electricity added to it is increased?

• The motor will slow down.

• The motor will speed up.

• The motor will stop working.

• The motor will reverse direction.

Answer explanation

As the amount of electricity supplied to an electric motor increases, the motor receives more power, which typically causes it to speed up. Therefore, the correct expectation is that the motor will speed up.

3) What kind of energy change does a generator perform?

• Mechanical to electrical

• Electrical to mechanical

• Chemical to electrical

• Thermal to mechanical

Answer explanation

A generator converts mechanical energy, typically from a rotating turbine, into electrical energy. This process is fundamental in power generation, making 'Mechanical to electrical' the correct choice.

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5) Which electromagnet below would be stronger: a nail wrapped with 40 coils of wire or a nail wrapped with 60 coils of wire?

• A nail wrapped with 40 coils of wire

• A nail wrapped with 60 coils of wire

Answer explanation

A nail wrapped with 60 coils of wire will be stronger because the strength of an electromagnet increases with the number of wire coils. More coils create a stronger magnetic field.

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