Electromagnetic Induction Ques 22
22. A varying current in a coil changes from $10$ $A$ to zero in $0.5$ $ sec$. If the average e.m.f induced in the coil is $220 $ $V$, the self-inductance of the coil is
[1995]
(a) $5 $ $H$
(b) $6 $ $H$
(c) $11 $ $H$
(d) $12 $ $H$
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Answer:
Correct Answer: 22.(c)
Solution:
- (c) Initial current $(I_1)=10 $ $A$;
Final current $(I_2)$ $=0$;
Time $(t)=0.5$ $ sec$ and induced e.m.f. $(\varepsilon)=$ $220 $ $V$.
Induced e.m.f. $(\varepsilon)$
$=-L \frac{d I}{d t}=-L \frac{(I_2-I_1)}{t}=-L \frac{(0-10)}{0.5}=20 $ $L$
or, $L=\frac{220}{20}=11 $ $H$
[where $L=$ Self inductance of coil]
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