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:

  1. The induced electric field is given by,

$$ \begin{aligned} & \oint \mathbf{E} \cdot \mathbf{d} \mathbf{l}=-\frac{d \varphi}{d t} \text { or } E l=-s \quad \frac{d B}{d t} \\ \therefore \quad E(2 \pi R) & =-\left(\pi R^{2}\right)(B) \text { or } E=-\frac{B R}{2} \end{aligned} $$



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