Testing & TroubleshootingQuestion 521 of 521
A 120 V heater is rated 600 W. What is the operating resistance of its element (assume purely resistive)?
a.5 ohms
b.0.2 ohms
c.24 ohms
d.72,000 ohms
Explanation
Using R = V^2 / P = (120 V)^2 / 600 W = 14,400 / 600 = 24 ohms. Equivalently, I = P / V = 5 A, then R = V / I = 120 / 5 = 24 ohms. Option a is the current in amps, and d multiplies V^2 x P.
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