Threshold energy of A EA = hvA = 6.6 x 10−34 x 1.8 x 1014 = 11.88 x 10−20 J =
11.88×10−20
1.6×10−19
eV = .74 eV Similarly, EB = 0.91 eV As the incident photons have energy greater than EA but less than EB So, photoelectrons will be emitted from metal A only.