Power of Electrical Circuit: Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Power of Electrical Circuit. Understanding the underlying formula is key to arriving at the correct answer below:

Since resistance $R = \frac{V^2}{P}$ and both have the same voltage rating, $R$ is inversely proportional to $P$. The $40\text{ W}$ bulb has lower power, so it must have higher resistance: $R_{40} > R_{100}$.