Question:medium

An electric bulb rated 200 V - 100 W is connected to a 160 V power supply. The power consumed by it would be:

Updated On: Mar 27, 2026
  • 64 W
  • 80 W
  • 100 W
  • 125 W
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The Correct Option is A

Solution and Explanation

Device power consumption is determined by the applied voltage and the device's resistance.

The power formula is:

\(P=\frac{V^2}{R}\)​.

The bulb's resistance R can be calculated from its rated voltage and power, which are 200 V and 100 W, respectively.

Using the formula

\(R = \frac{V_{\text{rated}}^2}{P_{\text{rated}}} = \frac{200^2}{100} = 400 \, \Omega\)

Next, we calculate the power consumed at an applied voltage of 160 V using the same formula:

\(P = \frac{160^2}{400} = \frac{25600}{400} = 64 \, W\)

Therefore, the bulb consumes 64 W when connected to a 160 V power supply.

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