Q. 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 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 $mA$
Explanation
(c) Amplitude of $ac = i_{0} = \frac{V_{0}}{R} = \frac{\omega NBA}{R} = \frac{(2\pi v)NB(\pi r^{2})}{R}$
$\Rightarrow i_{0} = \frac{2\pi \times \frac{200}{60} \times 1 \times 10^{- 2} \times \pi \times (0.3)^{2}}{\pi^{2}} = 6\ mA$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.