Question

A current of $5\,A$ is flowing at $220 \,V$ in the primary coil of a transformer. If the voltage produced in the secondary coil is $2200\, V$ and $50\%$ of power is lost, then the current in the secondary will be

• A. 2.5 A
• B. 5 A
• C. 0.25 A
• D. 0.5 A

Answer 1

Answer: (C)

$V_{p}=220 V , V_{s}=2200 V , I_{p}=5 A , I_{s}=?$
Power loss $=50 \%$
Efficiency of transformer $(\eta)$ is defined as the ratio of output power and input power
ie, $\eta \%=\frac{P_{\text {out }}}{P_{\text {in }}} \times 100 =\frac{V_{s} I_{s}}{V_{p} I_{p}} \times 100 $
$50 =\frac{2200 \times I_{s}}{220 \times 5} \times 100$
$I_{s} =0.25 \,A$