A wheel with `10` spokes each of length 'L' m is rotated with a unifrom angular velocity `omega` in a plane normal to the magnetic field 'B' . The emf induced between the axle and the rim of the wheel.

Explanation

N = 6, r = l = 0.6 m, B = 0.40 `G=0.40 xx 10^(-4) T`
f =60 rpm = 1rps
As the wheel is rotating, linear velocity of spoke at rim is `romega` and at the axel is 0.
`:. "Average linear velocity"=(romega+0)/(2)=(1)/(2)romega`
`"Induced emf"=e=Bvl=0.40 xx 10^(-4) xx (1)/(2) romega xx 0.6`
(As `omega=2pif`)
`:. e=0.40 xx 10^(-4) xx (1)/(2) xx 0.6 xx 2 xx 3.14 xx 1`
`e=7.5 xx 10^(-5) V`
All spokes in a wheel are connected in parallel therefore, net emf is equal to induced emf across each spoke.