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A monochromatic light is incident on a metallic plate having work function . An electron, emitted normally to the plate from a point A with maximum kinetic energy, enters a constant magnetic field, perpendicular to the initial velocity of electron. The electron passes through a curve and hits back the plate at a point B . The distance between A and B is : (Given : The magnitude of charge of an electron is e and mass

Options

  1. A2 ~m ( hc - ) / eB
  2. Bm ( hc - ) / eB
  3. C8 ~m ( hc - ) / eB
  4. D2 ~m ( hc - ) / eB

Correct answer

C. 8 ~m ( hc - ) / eB

Step-by-step solution

aligned & KE _ = hc - & p = 2 mK _ & p = 2 ~m ( hc - ) & d _ A - B =2 R & =2 [ p qB ] aligned d _ AB = 2 2 ~m ( hc - ) eB = 8 ~m ( hc - ) eB

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