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Question: Answered & Verified by Expert
In the figure, a charged sphere of mass m and charge q starts sliding from rest on a vertical fixed circular track of radius R from the position shown. There exists a uniform and constant horizontal magnetic field of induction B. The maximum force exerted by the track on the sphere is -


PhysicsMagnetic Effects of CurrentNEET
Options:
  • A mg
  • B 3mg- qB2gR
  • C 3mg+qB2gR
  • D mg- qB2gR
Solution:
2611 Upvotes Verified Answer
The correct answer is: 3mg+qB2gR
Fm=q v B (directed radially outward)

 N- mg sinθ- q v B=mv2R

or N=mv2R+mg sinθ+qvB

θ=π/2

Hence at θ=π/2

Nmax=2mgRR+mg+qB2gR

=3mg+qB2gR

Nmax=3mg+qB2gR

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