DC circuitsQuestion 570 of 1506

An 18 V battery supplies a lamp of 3 ohms. What power does the lamp dissipate?

  1. 6 W
  2. 108 W
  3. 54 W
  4. 324 W
Show answer

Correct answer: 108 W

I = 18 / 3 = 6 A, then P = 6 A x 18 V = 108 W.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 2.4: Calculating Electric Power

Practice dc circuits

Questions last reviewed: 18 October 2026