Question

A current of $2\text{mA}$ was passed through an unknown resistor which dissipated a power of $4.4\text{W}$. Dissipated power when an ideal power supply of $11\text{V}$ is connected across it is

• A. $11\times {10}^{-5}\text{W}$
• B. $11\times {10}^{-3}\text{W}$
• C. $11\times {10}^{-4}\text{W}$
• D. $11\times {10}^5\text{W}$

Answer 1

The correct option is A $11\times {10}^{-5}\text{W}$

Power disspiated across a resistor is,
$P=I^{2}R=\frac{v^2}{R}$
$\Rightarrow 4.4=4\times {10}^{-6}\times R$
$\Rightarrow R=1.1\times {10}^6\Omega$
Now Using,
$P=\frac{v^2}{R}=\frac{{11}^2}{1.1\times {10}^6}$
$P=11\times {10}^{-5}\text{W}$