A rectangular loop with a sliding connector of length `l=1.0 m` is situated in a uniform magnetic field `B=2T` perpendicular to the plane of loop. Resistance of connector is `r=2Omega`.Two resistance of `6Omega` and `3Omega` are connector is `r=2Omega`. two resistance of `6Omega` and `3Omega` are connected as shown in figure. the external force required to keep the connector moving with a constant velocity `v=2m//s` is

Options

A. `6N`
B. `4N`
C. `2N`
D. `1N`

Answer

C

Explanation

Motional emf `e=Bvlimpliese=2xx2xx1=4V`
this acts as a cell of emf `E=4V` and internal resistance `r=2pi`.
this simple circuit can be drawn as follows
current through the connector `i=(4)/(2+2)=1A`
:. Magnetic force on connector `F_(m)=Bil=2xx1xx1=2N`
(Towards left)