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NEET 2007

Exam: NEET
Year: 2007
Subject: Physics
Chapter: Alternating Current

NEET 2007 · Physics · Alternating Current

A transformer is used to light a 100 ~W and 110 ~V lamp from a 220...

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.

Options

A $50 \%$
B $90 \%$
C $10 \%$
D $30 \%$

Correct answer

B. $90 \%$

Step-by-step 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}

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