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Flashcards in P3 - Magnetic Fields Deck (11)
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1
Q

An electric motor produces a turning force. Give two ways in which to increase the turning force.

A

Increase the current/increase the number of turns on the coil/increase the area of the coil/increase the strength of the magnetic field

2
Q

Which appliances have an electric motor: electric drill, electric kettle, electric fan, electric iron, electric food mixer and electric screwdriver?

A

electric drill, electric fan, electric food mixer and electric screwdriver

3
Q

Give two ways of reversing the direction of the forces on a coil in an electric motor.

A

Reverse the direction of the current or the direction of the magnetic field.

4
Q

In what circumstance will no force act on a conductor carrying an electric current in a magnetic field?

A

When the conductor is parallel to the magnetic field or the lines of magnetic force and path of electricity do not cross.

5
Q

Why is the core of a transformer made of iron?

A

It is easily magnetised.

6
Q

Give two advantages of having a National Grid system.

A

Fewer power stations are needed; electricity can be generated remote from customers; power is available in remote areas; better control of demand and supply

7
Q

What does a step down transformer do?

A

It decreases the p.d.

8
Q

Give one advantage of using a switch mode transformer, rather than a traditional transformer inside mobile phone chargers.

A

Lighter, smaller, uses little power, more efficient

9
Q

Why must a mains adapter contain a transformer?

A

To reduce the mains p.d.

10
Q

Describe what happens when an alternating potential difference is applied across the primary coil of a transformer.

A

The alternating p.d. in the primary coil causes an alternating field in the iron core which induces alternating p.d. across the secondary coil.

11
Q

Why are the primary and secondary coils of a transformer made of insulated wire?

A

So that there is no short circuit and the current does not enter the core.