Question

A circular coil of 500 turns of wire has an enclosed area of $0.1m^{2}$ per turn. It is kept perpendicular to a magnetic field of induction 0.2 T and rotated by 180° about a diameter perpendicular to the field in 0.1 sec. How much charge will pass when the coil is connected to a galvanometer with a combined resistance of 50 ohms

• A. 0.2 C
• B. 0.4 C
• C. 2 C
• D. 4 C

Answer 1

Answer: (B)

0.4 C

Answer 2

$\Delta Q = \frac{NBA}{R}\left( \cos\theta_{1} - \cos\theta_{2} \right)$

$= \frac{500 \times 0.2 \times 0.1\left( \cos 0 - \cos 180 \right)}{50} = 0.4\mspace{6mu} C$