Question

The following figure shows a conducting disc rotating about its axis in a perpendicular magnetic field B. The resistor of resistance R is connected between the centre and the rim. The current in the resistor is (The radius of the disc is 5.0 cm, angular speed w = 10 radian/sec., B = 0.40 T and R = 10W.)

• A. 0.5A
• B. 0.2A
• C. 0.3A
• D. 0.9A

Answer 1

Answer: (A)

0.5A

Answer 2

Emf induced between centre and circum

e = $\frac{Β\omega a^{2}}{2}$, a ® radius

\ i =$\frac{\varepsilon}{R}$=$\frac{B\omega a^{2}}{2R}$ = $\frac{0.4 \times 10 \times (5 \times 10^{- 2})^{2}}{2 \times 10}$= 0.5A