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One conducting U tube can slide inside a...

One conducting U 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 maoves 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

A

`Blv`

B

`-Blv`

C

zero

D

`2 Blv`

Text Solution

Verified by Experts

The correct Answer is:
D

Relative velocity =`upsilon-(-upsilon)=2upsilon=(dl)/(dt)`
Now `e=(dphi)/(dt)`
`e=(Bldl)/(dt) ((dl)/(dt)=2upsilon)`
Inducted `emf e=2 Blupsilon`
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