A wheel with 8 metallic spokes is 50 cm long is rotated with the speed of 120 rev/min in a plane normal to the horizontal component of the earth magnetic field. The Earth's magnetic field at the place of 0.4 G and the angle of dip is `60^(@)`. Calculate the emf induced between the axel and the rim of the wheel. How will the value of emf be affected if the number of spokes were increased.

Explanation

`H = B cos theta = 0.4 cos 60^(@)`
`= 0.2 G = 0.2 xx 10^(-4)T`
This component is parallel to the plane of the wheel. Thus, the emf induced is
`E = (1)/(2) Bl^(2) omega`, where `omega = (2pi N)/(t)`
`:. E = (1)/(2) xx 0.2 xx 10^(-4) xx (0.5)^(2) xx (2 xx 3.14 xx 120)/(60)`
`= 3.14 xx 10^(-5) V`.
The value of emf will not be affected if number of spokes were increased.