Question

A metal disc of diameter 20cm rotate at a constant speed of 600 revolution per minutes about an axis through the centre and perpendicular to it's plane in a uniform magnetic field of value 5×10(-3)T established parallel to the axis of rotation. Calculate the EMF in bolts between the centre and the rim of the disc. Show clearly on a diagram the direction of the magnetic field and the EMF induced

Answer 1

$\varepsilon =-\frac{\Delta \Phi}{\Delta t}=-S\frac{\Delta B}{\Delta t}=\frac{\pi d^2 B \nu}{4},$

$\varepsilon=\frac{3.14\cdot 0.2^2\cdot 5\cdot 10^{-3}\cdot\frac{600}{60}}{4}=1.57~mV.$