Question

A (100 W, 200 V) bulb is connected to a 160 volts supply. The power consumption would be

• A. 100 W
• B. 125 W
• C. 64 W
• D. 80 W

Answer 1

The Correct Option is C

To find the power consumption of the bulb when connected to a different voltage supply, we need to use the relationship between power, voltage, and resistance. The formula for power is given by:

P = \frac{V^2}{R}, where P is power, V is voltage, and R is resistance.

First, we need to find the resistance of the bulb using its rated power and voltage:

1. The resistance R of the bulb can be calculated using its rated values: R = \frac{V_{\text{rated}}^2}{P_{\text{rated}}}
2. Substitute the rated values:
   R = \frac{200^2}{100} = \frac{40000}{100} = 400 \, \text{ohms}
3. Now, using this resistance, we calculate the power consumed when the bulb is connected to a 160 V supply:
   P_{\text{actual}} = \frac{V_{\text{actual}}^2}{R}
4. Substitute the actual values:
   P_{\text{actual}} = \frac{160^2}{400} = \frac{25600}{400} = 64 \, \text{W}
5. Thus, the power consumption of the bulb when connected to 160 V supply is 64 W.

Therefore, the correct answer is 64 W.