Light of frequency 7.21 x 1014 Hz is incident in a metal surface. Electrons with a maximum speed of 6.0 x 105 m/s are ejected from the surface. What is the threshold frequency for photoemission of electrons?
Frequency of light, υ=7.21×1014Hz Vmax=6.0×105m/s m=9×10−31kg applying Cinstein's photoelectric equation, K.E.max=21mVmax2=h(υ−υ0) 21mVmax2=h(υ−υ0) υ0=υ−2hMVmax2 υ0=7.21×1014−2×(6.63×10−34)(9.1)×10−31×(6×105)2 υ0=4.74×1014Hz
