A steady current of 2A flows in a coil of emf 12V for 0.4s. A back emf of 3V was induced during this period. The stored energy in the loop that can be utilized is?

A. 9.6J
B. 2.4J
C. 12.0J
D. 7.2J

Correct Answer:

Option B – 2.4J

Explanation

Energy stored = Ivt = current x back e.m.f x time
= 2 x 3 x 0.4
= 2.4J