First slide
Magnetic flux and induced emf
Question

A rod PQ of mass ‘m’ and resistance ‘r’ is moving on two fixed, resistance less, smooth conducting rails (closed on both sides by resistance  R1 and  R2). Then the current in the rod at the instant when its velocity V  is (A uniform magnetic field  B exists in the region)

Moderate
Solution

Given mass= m
Equivalent Resistance of R1  and  R2 in parallel =R1R2R1+R2
Velocity= V
We know current  i=er+Req
Also,  e=BlV
Then , 
i=BlVr+R1R2R1+R2 
Therefore, the correct answer is (D).
 

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