n electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be:A 100 W B 75 W C 50 W D 25 W
Question
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be:
- A. 100 W
- B. 75 W
- C. 50 W
- D. 25 W
Solution
The power P of an electric device is given by the formula P = V^2/R, where V is the voltage and R is the resistance.
Step 1: First, we need to find the resistance of the bulb when it is operated at its rated voltage. We can rearrange the formula to R = V^2/P.
Step 2: Substituting the given values, we get R = (220)^2/100 = 484 ohms.
Step 3: Now, we need to find the power consumed when the bulb is operated at 110 V. We can use the formula P = V^2/R again.
Step 4: Substituting the values, we get P = (110)^2/484 = 25 W.
So, the power consumed when the bulb is operated at 110 V is 25 W. Therefore, the answer is D. 25 W.
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