Question

To provide electricity to a laptop computer, a step-down transformer is used to reduce an alternating potential difference of 230 V to 15 V. The current that flows through the laptop is 2.5 A, calculate the current drawn by the primary coil of the step-down transformer. Give your answer to 2 significant figures.

Answer 1

Answer: Pp=Ip Vp=IsVs=Ps

Explanation: Assuming, as we have, that resistance is negligible, the electrical power output of a transformer equals its input. This is nearly true in practice—transformer efficiency often exceeds 99%. Equating the power input and output.