The correct options are A
Threshold frequency for the metal is 1.2×1015Hz
B Work function of the metal is 4.968 eV. C Maximum kinetic energy of photoelectrons corresponding to light of wavelength 100 nm is nearly 7.4 eV.KEmax
is zero corresponding to λ
= 250nm. Hence v=cf=3×108250×10−9=1.25×1015Hz
Work function (W) =1240λ(in nm)ev=4.96eV
For λ=100 nm; E=1240λ=124 ev. HenceKEmax=12.4−4.96≃7.4eV Red light not cause photoelectric effect as the energy is very less.