Question

A $220\text{volt}$ input is supplied to a transformer. The output circuit draws a current of $2.0\text{ampere}$ at $440\text{volts}$. If the efficiency of the transformer is $80\%$, the current drawn by the primary windings of the transformer is –

• A. $3.6\text{ampere}$
• B. $2.5\text{ampere}$
• C. $2.8\text{ampere}$
• D. $5.5\text{ampere}$

Answer 1

The correct option is D $5.5\text{ampere}$

Efficiency of transformer is given by,

$\eta =\frac{V_S{I}_S}{V_P{I}_P}$

$\Rightarrow I_P=\frac{V_S{I}_S}{V_P\eta }=\frac{\left(440\right)\left(2.0\right)}{\left(0.8\right)\left(200\right)}=5.5\text{A}$

Hence, $\left(D\right)$ is the correct answer.