Question

The current through two identical light bulbs connected in series is 0.25 A. The total voltage across both

bulbs is 120 V. The resistance of a single light bulb is

a. 48 ohms.

b. 240 ohms.

c. 480 ohms.

Answer 1

Given that, two identical bulb is connected in series.

current (I) = 0.25 A

total voltage across both (V) = 120 V

since, both the bulbs are identical therefore, both have equal resistance.

let, resistance of each bulb = R ohm

both are connected in series therefore total resistance = R + R = 2 R

now from Ohm's law ,

potential difference = current x resistance

or, 120 = 0.25 x 2 R = 0.5 R

or, R = 120/ 0.5

or, R = 240 ohms

hence, correct option is b. 240 ohms