ENERGY IN TRANSFORMERS

3 marks · Normal

A transformer has an input voltage of 240 V and an input current of 0.50 A. The transformer is 100% efficient. The output voltage is 12 V.

(a)

Calculate the current in the output circuit.

[3 marks]

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

10 A (±0.1)

Also accept: 10.0 A

Common mistakes: Dividing instead of multiplying or using wrong formula

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Substitute values into input power = output power: (240 V × 0.5 A) = (12 V × I_s) (follow-through)

M2 (a) · 1 mark · Rearrange to solve for I_s. (follow-through)

A1 (a) · 1 mark · Obtain correct value: I_s = 10 A.

Worked solution

Input power = output power (100% efficient)

Substitute the values: