Alternating Current Ques 16
16. A coil has resistance $30$ $ ohm$ and inductive reactance $20$ $ ohm$ at $50$ $ Hz$ frequency. If an ac source, of $200$ volt, $100$ $ Hz$, is connected across the coil, the current in the coil will be
[2011 M]
(a) $4.0 $ $A$
(b) $8.0 $ $A$
(c) $\frac{20}{\sqrt{13}} $ $A$
(d) $2.0 $ $A$
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Answer:
Correct Answer: 16.(a)
Solution:
- (a) If $\omega=50 \times 2 \pi$ then $\omega L=20$ $ \Omega$
If $\omega^{\prime}=100 \times 2 \pi$ then $\omega^{\prime} L=40 $ $\Omega$
Current flowing in the coil is
$I=\frac{200}{Z}=\frac{200}{\sqrt{R^{2}+(\omega^{\prime} L)^{2}}}=\frac{200}{\sqrt{(30)^{2}+(40)^{2}}}$
$I=4$ $ A$.
BETA
