MHT CET202211 Aug 2022Morning ShiftPhysicsElectromagnetic InductionActual
A long, rectangular conducting loop of width l mass m and resistance R is placed partly in a perpendicular magnetic field B . It is pushed downwards with velocity v so that it may continue to fall freely. The velocity v is (g= acceleration due to gravity)
Options
- Am g R^2 B l
- Bm g R B^2 l^2
- Cm g l B^2 R^2
- DB^2 l^2 R m g
Correct answer
B. m g R B^2 l^2
Step-by-step solution
The motional emf is given by: V=B v l Current in the loop, i= V R = B v l R During free fall the electromagnetic force felt by the loop balances its weight, and since the loop is long so we assume its falling with a terminal velocity. aligned & i l B=m g & B ( B v l R ) l=m g & v= m g R B^2 l^2 aligned