A uniform circular metal disc of radius `R` is rotating about a vertical axis passing through its centre and perpendicular to its plane with constant frequency f. If `B_(H)` and `B_(V)` are horizontal and vertical components of the Earth's magnetic field respectively, then the induced e.m.f between its centre and the rim is

Options

A. `pi B_(V) f R^(2)`
B. `pi B_(H) f R^(2)`
C. `2 pi B_(V) f R^(2)`
D. Zero

Answer

A

Explanation

`e = (1)/(2) BR^(2) omega` where `omega = 2 pi f`