1.

The work function of caesium is 2.14 eV. When light of frequency `6xx10^(14)Hz` is incident on the metal surface, photoemission of electrons occurs. What is the (a) maximum kinetic energy of the emitted electrons. (b) stopping potential and (c) maximum speed of the emitted photoelectrons. given , `h=6.63xx10^(-34)Js, 1eV=1.6xx10^(-19)J, c=3xx10^(8)m//s`.

Answer» (a) Max. K.E. `=hv-phi_(0)=(6.63xx10^(-34)xx6xx10^(14))/(1.6xx10^(-19))-2.14=0.346eV=0.35eV`
(b) `eV_(0)=Max. K.E. =0.35 eV or V_(0)=0.35eV`
(c) `1/2mv_(max)^(2)=0.346 eV=0.346xx1.6xx10^(-19)J`
of `v_(max)=((0.346xx1.6xx10^(-19)xx2)/(9.1xx10^(-31)))^(1//2)=3.488xx10^(5)m//s=348.8 km//s =349kms^(-1)`


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