A circular copper disc 10 cm in radius rotates at $20\pi$ rad/s about an axis through its centre and perpendicular to its disc. A uniform magnetic field of 0.2T acts perpendicular to the disc. Calculate the induced current if the resistance of the disc is $2\Omega$.

Question

(a) 0.315 A
(b) 0.0315 A
(c) 3.15 A
(d) 31.5 A