Q133 / 200 · NEET 2007 · Physics

A transformer is used to light a $100 \mathrm{~W}$ and $110 \mathrm{~V}$ lamp from a $220 \mathrm{~V}$ mains. If the main current is $0.5 \mathrm{amp}$, the efficiency of the transformer is approximately.

  • A
    $50 \%$
  • Correct answer
    B
    $90 \%$
  • C
    $10 \%$
  • D
    $30 \%$

Solution

The efficiency of transformer $\begin{aligned} \eta & =\frac{V_s I_s}{V_p I_p} \times 100 \\ & =\frac{100}{220 \times 0.5} \times 100=90 \% \end{aligned}$

Hence, the correct answer is option: 'B'.

Relevant Questions