question_answer

One conducting 17-tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed v, then the emf induced in the circuit in terms of B, l and v, where l is the width of each tube, will be     AIEEE  Solved  Paper-2005

A) \[BIl\]       

B)                        \[-BIl\] 

C)        zero                

D)        \[2\,BIl\]

Correct Answer: D

Solution :

Relative velocity of tubes with respct to each other Now, emf induced in circuit made by two tubes is