Alternating Current - Result Question 10
10. In a region of uniform magnetic induction $B=10^{-2}$ tesla, a circular coil of radius $30 cm$ and resistance $\pi^{2} ohm$ is rotated about an axis which is perpendicular to the direction of $B$ and which forms a diameter of the coil. If the coil rotates at $200 rpm$ the amplitude of the alternating current induced in the coil is
(a) $4 \pi^{2} mA$
(b) $30 mA$
(c) $6 mA$
(d) $200 mA$
[1988]
Topic 2: A.C. Circuit, LCR Circuit,
Quality & Power Factor
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Answer:
Correct Answer: 10. (c)
Solution:
(c) $I_0=\frac{E_0}{R}=\frac{n B A \omega}{R}$
Given, $n=1, B=10^{-2} T$,
$A=\pi(0.3)^{2} m^{2}, R=\pi^{2}$
$f=(200 / 60)$ and $\omega=2 \pi(200 / 60)$
Substituting these values and solving, we get $I_0=6 \times 10^{-3} A=6 mA$
