Topic 6 - Transformers (Paper 2)

Question 1

what do transformers do?

Answer 1

change the size of the voltage of an alternating current

Question 2

what are transformers made of?

Answer 2

a primary and secondary coil joined with an iron core

Question 3

what happens when an alternating voltage is applied across the primary coil?

Answer 3

the magnetically soft core magnetises and demagnetises quickly, inducing a voltage in the secondary coil

Question 4

what is a step-up transformer?

Answer 4

a transformer that increases the voltage. it has more turns on the secondary coil

Question 5

what is a step-down transformer?

Answer 5

a transformer that decreases the voltage. it has more turns on the primary coil

Question 6

what is the transformer equation?

Answer 6

input voltage / output voltage = primary number of turns / secondary number of turns

Question 7

what is the formula for power supplied?

Answer 7

power = voltage x current

Question 8

what is the formula for input power?

Answer 8

primary voltage x primary current = secondary voltage x secondary current

Question 9

how are transformers used in mains electricity?

Answer 9

1. voltage produced by power stations is too low to be transmitted efficiently.
2. step-up transformers boost the voltage
3. step-down reduced the voltage after its transmitted so its more useful and safer to use