Electromagnetic Induction and Alternating Current: Back EMF Calculation MCQ

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Back EMF CalculationHardQuestion 20230

Question

A DC motor draws 10 A from a 200 V supply. Its armature resistance is 2 Ω. Back EMF is:

A
180 V
Correct
B
220 V
C
200 V
D
20 V

Correct answer

180 V

Explanation

Back EMF ε = V − IR = 200 − 10×2 = 180 V. The motor converts 180V×10A = 1800 W to mechanical power, while 10²×2 = 200 W is lost as heat in the armature.

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