Rod `PQ` of length `2l` is rotating about one end `P` in a uniform magnetic field `B` which is perpendicular to the plane of rotation of the rod . Point `M` is the mid- point of the rod. Find the induced emf between `M` and `Q` if the potential between `P` and `Q` is `100 V`.

Explanation

`E_(PQ) = (1)/(2)Bomega(2l)^(2) = 100 V `rarr` omegal^(2) = 50 V`
`E_(PM) = (1)/(2)Bomega(l)^(2) = 25 V`
`E_(MQ) = E_(PQ) - E_(PM) = 100 - 25 = 75 V`