Red Seal Electrician Practice
Electrical mathQuestion 1119 of 1506

A 2000 W heating element is rated for 240 V. It is connected directly to a 120 V supply. About how much power does it dissipate?

  1. 1000 W
  2. 500 W
  3. 2000 W
  4. 250 W
Show answer

Correct answer: 500 W

The resistance stays the same, so half the voltage gives half the current and one quarter of the power: 2000 W / 4 = 500 W.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.7: Special Transformers and Applications

Practice electrical math

Questions last reviewed: 18 October 2026