Paper 2 H - SAMPLE SET 1 Q23
23) The diagram below shows the structure of a transformer.
(a) Explain why there is more alternating current in the secondary coil than in the first. [3]
(b) The secondary coil produces an output of 12 V.
Calculate the number of turns needed on the secondary coil.
Show your working. [2]
(c) Voltage is increased before transmission through the National Grid.
It is increased from 25 000 V up to 400 000 V. This increases the voltage 16 times.
(i) How much would this increase in voltage affect the current? [2]
(ii) Use the formula:
(b) The secondary coil produces an output of 12 V.
Calculate the number of turns needed on the secondary coil.
Show your working. [2]
(c) Voltage is increased before transmission through the National Grid.
It is increased from 25 000 V up to 400 000 V. This increases the voltage 16 times.
(i) How much would this increase in voltage affect the current? [2]
(ii) Use the formula:
power = current2 x resistance
to explain why this voltage increase is important to power loss in transmission cables. [2]
(Total for Question 23 = 9 marks)