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NTA Abhyas JEE Main2020PhysicsMagnetic Effects of CurrentPractice

A block of mass m and charge q is released on a long smooth inclined plane. Magnetic field B is constant, uniform and out of the plane of the paper as shown. Find the time from the start when blocking lose contact with the surface.

Options

  1. Am cosθ qB
  2. Bm cosec θ qB
  3. Cm cotθ qB
  4. Dm tanθ qB

Correct answer

C. m cotθ qB

Step-by-step solution

Block will lose contact with surface when force due to magnetic field will become equal to mgcosθ qvB = mgcosθ v = mgcosθ qB = u + at ( along inclined plane ) v = mgcosθ qB = ( g  sin θ ) t t =   m cot θ qB

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