3.19 How Transformers work

Question 1

What do transformers do?

Answer 1

Transformers change the size of the potential difference of an alternating current

Question 2

What do transformers consist of?

Answer 2

Two coils of wire, the primary and secondary, joined with an iron core.

Question 3

What voltage do step up transformers increase the voltage to?

Answer 3

Around 400,000 V

Question 4

Why do step up transformers increase the voltage to around 400,000V?

Answer 4

To minimise energy loss as the energy is sent across the country in a huge network of wires and pylons.

Question 5

What voltage do step down transformers decrease the voltage to?

Answer 5

To around 230 V

Question 6

Why do step down transformers decrease the voltage to around 230 V?

Answer 6

So it is safe to use in homes

Question 7

Describe how transformers work

Answer 7

An alternating potential difference is applied across the primary coil which causes a current to flow and generates a magnetic field around the coil. As the potential difference is alternating, the direction of the current and the magnetic field will also alternate. This alternating magnetic field in the primary coil induces an alternating magnetic field in the iron core. The iron core’s magnetic field induces a potential difference across the secondary coil and this causes a current to flow around the secondary coil.

Question 8

Step - up transformers

Answer 8

Step-up transformers step the potential difference up (i.e. increase it). They have more turns on the secondary coil than the primary coil.

Question 9

Step - down transformers

Answer 9

Step-down transformers step the potential difference down (i.e. decrease it). They have more turns on the primary coil than the secondary coil.