An electric bulb is rated ' $100 W, 250 V$ ‘, The resistance of the bulb is:

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$1500 Ω$

2.5 $Ω$

$25000 Ω$

$625 Ω$

answer is B.

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Detailed Solution

Any conductor, even a lightbulb, will block the flow of an electric current; this obstruction is known as electrical resistance and is represented by the letter R. Conductors emit heat when current flows through them because all materials have an electrical resistance.

Given:
Lamp Power P = 100W
Lamp Voltage V = 250V
The power, voltage, and resistance relationship is given if
$R = V^{2} P$
R is tolerant of the lamp.
If you change the power and voltage values in the above equation, you get
$R = {(250 V)}^{2} / 100 W = 62500 / 100 = 625 Ω .$
Therefore, the correct answer is option B, or 625 $Ω$ .