A wheel with 10 metallic spokes, each 0.5 m long, is rotated with an angular speed of 120 rpm in a plane normal to the earth's magnetic field at the place. If the magnitude of the field is 0.4G, the magnitude of induced emf between the axle and the rim of the wheel is equal to

Options

A. ` 1.256 xx 10^(-3)V`
B. `6.28 xx 10^(-4) V`
C. `1.256 xx 10^(-4) V`
D. `6.28 xx 10^(-5)V`

Answer

D

Explanation

Here l=0.5m, `omega=120rpm=2rps=4pi rad s^(-1) and B=0.4 G=0.4 xx 10^(-4)T`
`epsi=1/2 Bl^(2) omega=1.2 0.4 xx 10^(-4)0 xx (0.5)^(2) xx (4pi) =6.28 xx 10^(-5)V`