Question

A transformer of efficiency $90\%$ has turns ratio $10:1.$ If the voltage across the primary is $220V$ and current in the primary is $0.5A,$ then the current in secondary is

• A. $5.5A$
• B. $5A$
• C. $4A$
• D. $4.5A$

Answer 1

Answer: (D)

Given, $\frac{N_P}{N_S}=\frac{10}{1}$
$V_P=220V,I_P=0.5A$
We know that, $\frac{V_P}{V_S}=\frac{N_P}{N_S}$
Efficiency, $\eta =\frac{Outputpower}{Inputpower}=\frac{I_S{V}_S}{I_P{V}_P}$
$\frac{90}{100}=\frac{I_S}{0.5}$ $\times \frac{1}{10}$
$\Rightarrow I_S=4.5A$