A 120VAC electric heater has two resistive heating elements that can be switched separately in and out, in series or parallel. Find the values of the two resistors if the minimum power drawn by the heater is 300 watts and the maximum is 1200 watts.

The values of the two resistors are 48 ohms and 12 ohms.

Explanation:

Power (P) = Voltage^2 (V^2) : Resistance (R)

R = V^2 : P

The minimum power drawn by the heater is 300 watts

Voltage is 120 V

R = 120^2 : 300 = 14,400:300 = 48 ohms

The maximum power drawn by the heater is 1200 watts

R = 120^2 : 1200 = 14,400 : 1200 = 12 ohms