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Heating Effect of Electric Current

A light bulb ...

Question

A light bulb uses energy at a rate of 25.0 Watts. If the current through light bulb is 2.00 A. What is the resistance of the bulb?

A

6.25 ohms

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B

12.5 ohms

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C

0.0800 ohms

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D

50.0 ohms

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E

100.0 ohms

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Solution

The correct option is C 6.25 ohms
Given : Power of the bulb $P = 25.0$ Watts
Current flowing through the bulb $I = 2.00$ A
Thus resistance of the bulb $R = \frac{P}{I^{2}} = \frac{25.0}{(2.00)^{2}} = 6.25$ ohms

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