How we worked it out
Updated as you change the numbers.
- V = I × R; P = V × I = I²R = V² ÷ R. Two known values fix the other two.
Method and assumptions
Ohm’s law relates voltage, current and resistance in a resistive circuit; the power formula follows from it. For AC circuits with motors or electronics, power also depends on the power factor.
Questions
How many amps does a 1,500 W heater draw at 120 V?
12.5 A.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.