THE TRANSFORMER
4 marks · NormalThe diagram shows a transformer. The secondary coil has 300 turns and produces a voltage of 15 V.
The primary coil has 1200 turns. Calculate the input voltage.
State whether this transformer is step-up or step-down. Give a reason for your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 60 V
(b) Step-down, because it reduces voltage from primary to secondary. · must show step-down, reduces voltage
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · States or uses or equivalent.
M2 (a) · 1 mark · Correct rearrangement for : .
A1 (a) · 1 mark · Substitutes values to give . (follow-through)
B1 (b) · 1 mark · Identifies step-down transformer and gives correct justification (primary voltage > secondary voltage, or voltage is reduced).
Worked solution
a) Use the transformer equation:
b) This is a step-down transformer because the secondary voltage (15 V) is lower than the primary voltage (60 V).