The threshold frequency for a certain metal is 3.3 x 1014 Hz. If the light of frequency 8.2 x 1014 Hz is incident on the metal, predict the cut-off voltage for the photoelectric emission.
Correct option is C) In photoelectric effect, energy is conserved. In photoelectric effect, Einstein's equation is given by Photon energy = kinetic energy of electron + work function i.e. hv=eVs+hv0 where, Vs is the stopping potential and v0 is the threshold frequency. ∴Vs=eh(v−v0) .....(i) Given, v0=3.3×1014Hz, v=8.2×1014Hz h=6.6×10−34J−s, e=1.6×10−19C Substituting these values in equation (i), we get Vs=1.6×10−196.6×10−34(8.2×1014−3.3×1014) Vs=1.66.6×4.9×10−1=2V ⇒Vs=2V
