Question

A motor in normal operation carries a direct current of 0.690 A when connected to a 120-V power supply. The resistance of in motor windings is 18.0 Ω. Determine the following values.

(a) While in normal operation, what is the back emf generated by the motor?
V

(b) While in normal operation, at what rate is internal energy produced in the windings?
W

(c) What If? Suppose that a malfunction stops the motor shaft from rotating. At what rate will internal energy be produced in the windings in this case? (Most motors have a thermal switch that will turn off the motor to prevent overheating when this occurs.)
kW

Answer 1

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