Question

A small bulb is rated at 7.5 W when operated at 125 V. Its resistance (in ohms) is : (a) 17 (b) 7.5 (c) 940 (d) 2100 (e) 0.45

Answer 1

Answer:

Resistance of the bulb is 2100 watts.

Explanation:

Given that,

Power of the bulb, P = 7.5 watts

Voltage, V = 125 volts

We have to find the resistance of the bulb. The power of an electrical appliance is given by the following formula as :

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

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

$R=\dfrac{(125\ V)^2}{7.5\ W}$

R = 2083.34 ohms

or

R = 2100 ohms

Hence, the correct option is (d) "2100 ohms"