A light bulb is rated at 100 W for a 220 V a.c. supply. Calculate the resistance of the bulb.

Explanation

To calculate the resistance of the light bulb rated at 100 W for a 220 V a.c. supply, we can follow these steps:

### Step 1: Understand the relationship between power, voltage, and resistance
The average power (P) in an AC circuit can be expressed using the formula:
\[ P = V_{\text{rms}} \times I_{\text{rms}} \]
where \( V_{\text{rms}} \) is the root mean square voltage and \( I_{\text{rms}} \) is the root mean square current.

### Step 2: Use Ohm's Law to relate current and resistance
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