Question

If power dissipated in 5Ω resistor in 20W, then power dissipated across 4Ω resistor will be.

(A) 1 W

(B) 2 W

(C) 3 W

(D) 4 W

Answer 1

The correct option (D) 4 W

Explanation:

from figure, V = I1 ∙ 5 = I2 ∙ 10

∴ I1 = 2I2

Power decapitated = P = I2R

for 5Ω resistor, 20 = I12 × 5

I12 = 4

I1 = 2A

∴ I2 = (I1 / 2) = (2/2) = 1A

∴ Power dissipated across 4Ω resistor = Ixad22 × R

= 12 × 4 = 4 W