Question

A step-down transformer connected to an AC mains supply of $220\text{V}$ is made to operate at $11\text{V},44\text{W}$ lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?

• A. $4.0\text{A}$
• B. $0.2\text{A}$
• C. $0.4\text{A}$
• D. $2.0\text{A}$

Answer 1

The correct option is B $0.2\text{A}$

In an ideal transformer,

Input power $=$ Output power

$\Rightarrow V_P{I}_P=V_S{I}_S$

$\Rightarrow 220\times I_P=44$

$\Rightarrow I_P=0.2\text{A}$

​​​​​​​Hence, option $\left(B\right)$ is the correct answer.