You have the following appliances each of 500 W running on 220 V a.c. (1) electric iron (2) electric lamp (3) electric room heater The electric resistance is

Options

A. maximum for room heater
B. maximum for electric iron
C. maximum for electric lamp
D. same in all the three cases

Answer

To find the electric resistance of the appliances (electric iron, electric lamp, and electric room heater), we can use the formula relating power (P), voltage (V), and resistance (R):

\[ P = \frac{V^2}{R} \]

From this formula, we can rearrange it to find the resistance:

\[ R = \frac{V^2}{P} \]

### Step-by-step Solution:

1. **Identify the given values**:
- Power (P) = 500 W
- Voltage (V) = 220 V

2. **Substitute the values into the resistance formula**:
\[ R = \frac{V^2}{P} \]
\[ R = \frac{(220)^2}{500} \]

3. **Calculate \( V^2 \)**:
\[ V^2 = 220 \times 220 = 48400 \]

4. **Substitute \( V^2 \) back into the formula**:
\[ R = \frac{48400}{500} \]

5. **Perform the division**:
\[ R = 96.8 \, \Omega \]

### Conclusion:
The electric resistance for each of the appliances (electric iron, electric lamp, and electric room heater) is approximately **96.8 ohms**.