Q. A circular ring of diameter 20 cm has a resistance of 0.01$\Omega$. The charge that will flow through the ring if it is turned from a position perpendicular to a uniform magnetic field of 2.0 T to a position to the field is about
A) 63 C
B) 0.63 C
C) 6.3 C
D) 0.063 C
Explanation
(c) $q = \frac{d\phi}{R} = \ \frac{BA(\cos\ 0{^\circ} - \cos{90{^\circ})}}{R}$
$= \ \frac{B\pi r^{2}(1 - 0)}{R} = \frac{B\pi r^{2}}{R} = \frac{2 \times 3.143 \times \left( 10^{- 1} \right)^{2}}{0.01}$
$= 6.286\ C = 6.3\ C$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.