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Question and Answer

A light bulb is rated at \(100W \)for a \(220 V\) supply. Find the resistance of the bulb
.

Answer

\(484\;\text{ohm}\)
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Solution

As we know that
\(\text{Power}=VI\) 
According to the question
\(P=100W \)and \(V=220V\)
By ohm's law \(V=IR\)
Current,
 \(I=\frac V R\)
Than, \(P=V\times \frac{V}{R}\)
\(P=\frac{{V}^{2}}{R}\)
Resistance \(=\frac{{V}^{2}}{P}\)
\(=\frac{{\left. \left(220\right)\right. }^{2}}{100}\)
\(=484\;\text{ohm}\)
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