Question

The current flowing in a coil of self inductance 0.4 mH is increased by 250 mA in 0.1 sec. The e.m.f. induced will be

• A.
  • 1 V
• B. – 1 V
• C.
  • 1 mV
• D. – 1 mV

Answer 1

Answer: (D)

– 1 mV

Answer 2

$e = - L\frac{di}{dt} = - 0.4 \times 10^{- 3} \times \frac{250 \times 10^{- 3}}{0.1} = - 1\mspace{6mu} mV$