Photoemission from metal surface take place for frequencies ' $v 1$ ' and ' $v_2$ ' of incident rays. If…

Photoemission from metal surface take place for frequencies ' $v 1$ ' and ' $v_2$ ' of incident rays. If ratio of maximum kinetic energy of photoelectrons is $1: \mathrm{K}$ then threshold frequency of metallic surface is
  1. $\frac{\mathrm{K} v_2-v_1}{\mathrm{~K}-1}$
  2. $\frac{v_1-v_2}{\mathrm{~K}-1}$
  3. $\frac{v_2-v_1}{\mathrm{~K}}$
  4. $\frac{\mathrm{K} v_1-v_2}{\mathrm{~K}-1}$

Asked in: MHT CET 2021 (21 Sep Shift 2)

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