Topic: Electromagnetics
Change in magnetic flux in coil of 30 turns is 0.1 weber/second. What is the value of induced EMF?
- A. 30 V
- B. -3 V
- C. 300 V
- D. -300V
Answer: B. -3 V
Explanation: According to Faraday's Law of Electromagnetic Induction, the induced EMF is given by $e = -N \frac{d\phi}{dt}$, where $N$ is the number of turns and $\frac{d\phi}{dt}$ is the rate of change of magnetic flux.
$e = -30 \times 0.1 = -3 V$. The negative sign indicates Lenz's Law.