A monochromatic light source of power 5mW emits 8X1015 photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this set up is 2V. Calculate the work function of the metal.

Dear Student,
Work function is given as
P=5×10-3 WNo. of electrons, n=8×1015V=2 Ve=1.6×10-19 C

The work function can be calculated as
W=5×10-38×1015-(1.6×10-19×2)=(6.25-3.2)×10-19W=3.05×10-19 JW=3.05×10-191.6×10-19=1.91×10-19 eV


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