Electromagnetic Induction and Alternating Current 7 Question 19
19. The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the magnetic field change is
(a) $\frac{B R}{4}$
(b) $\frac{-B R}{2}$
(c) $B R$
(d) $2 B R$
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Answer:
Correct Answer: 19. (b)
Solution:
- The induced electric field is given by,
$$ \begin{aligned} & \oint \mathbf{E} \cdot \mathbf{d} \mathbf{l}=-\frac{d \varphi}{d t} \text { or } E l=-s \quad \frac{d B}{d t} \\ \therefore \quad E(2 \pi R) & =-\left(\pi R^{2}\right)(B) \text { or } E=-\frac{B R}{2} \end{aligned} $$
