Question

A conducting disc of radius r rotates with a small constant angular velocity $\omega$ about its axis. A uniform magnetic field B exists parallel to the axis of rotations. Find the motional emf between the center and the periphery of the disc.

Answer 1

Rotating dics can be consider as a rotating rod of same radius.

v at a distance $r/2$ From the centre $=r\frac{w}{2}$

$E=Blv$

$E=B\times r\times \frac{rw}{2}$

$E=\frac{1}{2}B{r}^{2}w$