What is the power $P$ dissipated by a resistor of $R=5\Omega$ when a potential difference of $V=10\text{V}$ is applied across it?

Solution

1. The formula for power is $P=\frac{V^2}{R}$.
2. Substituting the given values, $P=\frac{10^2}{5}$.
3. Calculating the square, $P=\frac{100}{5}$.
4. The result is $P=20\text{W}$.
5. Hence the answer is (A).