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A rod AB of length L and mass m is unifo...

A rod AB of length L and mass m is uniformly charged with a charge Q, and it is suspended from end A as shown in fig. The rod can freely rotate about A in the plane of the figure. An electric field E is suddenly switched on in the horizontal direction due to which the rod gets turned by a maximum angle of `90^(@)`. The magnitude of E is equal of `nMg//Q`. Find the value of n.

Text Solution

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The correct Answer is:
1
After truning through `90^(@)` the rod comes at rest momentarily. So there is no change in KE. Net work done by all force should be zero.

`QE L/2-Mg L/2=0 or E=(Mg)/(Q)`.
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