A conducting wire `xy` of lentgh `l` and mass `m` is sliding without friction on vertical conduction rails `ab` and `cd` as shown in figure. A uniform magnetic field `B` exists perpendicular to the plane of the rails, `x` moves with a constant velocity of

Options

A. (a) `(mgR)/(Bl)`
B. (b) `(mgR)/(Bl^(2))`
C. ( c) `(mgR)/(B^(2)l^(2))`
D. (d) `(mgR)/(B^(2)l)`

Answer

C

Explanation

( c) `Bil = mg` or `B(Bvl)/(R )l = mg` or `v = (mg R)/(B^(2)l^(2))`