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A step-down transformer reduces the voltage of a transmission line from $2200 \mathrm{~V}$ to $220 \mathrm{~V}$. The power delivered by it is $880 \mathrm{~W}$ and its efficiency is $88 \%$. The input current is
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The correct answer is:
$0.45 \mathrm{~A}$
Efficiency of transformer,
$$
\begin{aligned}
\eta \quad \eta &=\frac{\text { Output po }}{\text { Input powe }} \\
\Rightarrow \quad \frac{88}{100} &=\frac{880}{P_{i}} \\
\Rightarrow \quad P_{i} &=1000 \mathrm{~W} \\
\text { Input current, } I_{P} &=\frac{P_{i}}{V_{i}} \\
&=\frac{1000}{2200} \\
&=0.45 \mathrm{~A}
\end{aligned}
$$
$$
\begin{aligned}
\eta \quad \eta &=\frac{\text { Output po }}{\text { Input powe }} \\
\Rightarrow \quad \frac{88}{100} &=\frac{880}{P_{i}} \\
\Rightarrow \quad P_{i} &=1000 \mathrm{~W} \\
\text { Input current, } I_{P} &=\frac{P_{i}}{V_{i}} \\
&=\frac{1000}{2200} \\
&=0.45 \mathrm{~A}
\end{aligned}
$$
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