What is the source voltage in a circuit that consumes 1200 watts at a current of 5 amps?

• A. 120 volts
• B. 480 volts
• C. 600 volts
• D. 240 volts

Answer: (D)

Power in a circuit is the product of voltage and current. So if you know the power and the current, you find the source voltage with V = P / I. Here, V = 1200 W / 5 A = 240 V. Therefore, the source voltage is 240 volts. If you check the other options: at 120 V the power would be 600 W, at 480 V it would be 2400 W, and at 600 V it would be 3000 W, none of which match the given 1200 W at 5 A.