5. Motors, Generators and Transformers

Question 1

What happens when a current flows through a wire?

Answer 1

A magnetic field is produced around the wire

Left hand grip rule

Question 2

What is the motor effect?

Answer 2

When a wire carrying a current is placed in a magnetic field and it experiences a force

Question 3

How do you determine the direction of force in the motor effect?

Answer 3

Lemmings left hand rule
Mother (motion)
Fuking (Force)
Cnt (Current)

Question 4

How can the size of the force be increased:

Answer 4

By increasing the strength of the magnetic field

By increasing the size of the current

Question 5

What happens if an electrical conductor ‘cuts’ through a magnetic field?

Answer 5

A potential difference is induced across the ends of the conductor

Question 6

What is the generator effect?

Answer 6

When a magnet moves into a coil of wire and a potential difference is induced across both ends of the coil

Question 7

The size of the induced potential difference (generator effect) increases when:

Answer 7

The speed of the movement increases
The strength of the magnetic field increases
The number of turns in the coil increases
The area of the coil increase

Question 8

Describe a basic transformer:

Answer 8

A basics transformer consists of a primary coil and a secondary coil wound on a soft iron core

Question 9

Switch mode transformers are transformers that:

Answer 9

Operate at a high frequency, often between 50 kHz and 200 kHz
Are much lighter and smaller than traditional transformers, so useful in things like mobile phone chargers
Use very little power when they are switched on but no load is applied