Question

A $220V$ input is supplied to a transformer. The output circuit draws a current of $2.0A$ at $440$ volts. If the efficiency of the transformer is 80%, the current drawn by the primary winding of the transformer is

• A. 3.6 ampere
• B. 2.8 ampere
• C. 2.5 ampere
• D. 5.0 ampere

Answer 1

The correct option is D 5.0 ampere

Efficiency of transformer, $\eta =80\%$
Efficiency of transformer,$\eta =\frac{Outputpower}{Inputpower}$
$\eta =\frac{V_S{I}_S}{V_P{I}_P}or{I}_P=\frac{V_S{I}_S}{\eta V_P}=\frac{\left(440V\right)\left(2A\right)\left(100\right)}{\left(80\right)\left(230V\right)}=5A$