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Current Electricity question

2006 · Shift 0 · Q118

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Current Electricity
2006 · Shift 0 · Q118

Current Electricity question

2006 · Shift 0 · Q118

JEE MainPhysicsCurrent ElectricityMCQ+4 / −1

An electric bulb is rated

220

volt -

100

watt. The power consumed by it when operated on

110

volt will be

A
$75$ watt
B
$40$ watt
C
$25$ Watt
D
$50$ Watt

View written solutionFree

Correct answer: C

Use the bulb's rated values to find its resistance

For a bulb rated $220\,\text{V}$ and $100\,\text{W}$ ,

$P = \frac{V^2}{R}$

So,

$R = \frac{V^2}{P} = \frac{(220)^2}{100} = \frac{48400}{100} = 484\,\Omega$

Find the power when operated at $110\,\text{V}$

Assuming the resistance remains the same,

$P' = \frac{V'^2}{R} = \frac{(110)^2}{484} = \frac{12100}{484} = 25\,\text{W}$

Match with the options

The power consumed is:

$25\,\text{W}$

So the correct option is C.

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