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JEE Main202117 Mar 2021Evening ShiftPhysicsDual Nature of MatterActual

Two identical photocathodes receive the light of frequencies f 1 and f 2 respectively. If the velocities of the photo-electrons coming out are v 1 and v 2 respectively, then

Options

  1. Av 1 2 - v 2 2 = 2   h   m [ f 1 - f 2 ]
  2. Bv 1 2 + v 2 2 = 2 h m f 1 + f 2
  3. Cv 1 + v 2 = 2   h   m f 1 + f 2 1 2
  4. Dv 1 - v 2 = [ 2   h   m f 1 - f 2 ] 1 2

Correct answer

A. v 1 2 - v 2 2 = 2   h   m [ f 1 - f 2 ]

Step-by-step solution

1 2 m v 1 2 = h f 1 - ϕ 1 2 m v 2 2 = h f 2 - ϕ v 1 2 - v 2 2 = 2 h   m f 1 - f 2

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