A transformer has 400 turns on the primary and 100 turns on the secondary. A $240\text{V rms}$ sinusoidal supply at $50\text{Hz}$ is connected to the primary. The secondary is connected to a resistive load of $800\Omega$. Find (a) the secondary rms voltage, and (b) the secondary rms current.

Step-by-step solution

1. The turns ratio is $\frac{N_p}{N_s}=\frac{400}{100}=4$, so the voltage ratio is $\frac{V_p}{V_s}=4$.
2. Hence $V_s=\frac{V_p}{4}=\frac{240\text{V}}{4}=60\text{V rms}$.
3. The secondary current follows $I_s=\frac{V_s}{R_{\text{load}}}=\frac{60\text{V}}{800\Omega }=0.075\text{A rms}$.

Concept tested: Transformer voltage and current ratios

Published 7 September 2026 · How this solution was prepared and checked