Q.
A and B are two metals with threshold frequencies 1.8×1014Hz and 2.2×104Hz
Two identical photons of energy 0.825eV each are incident on them. Then photoelectrons are emitted by (Take h=6.6×10−34J−s)
Threshold energy of A is EA=hvA =6.6×10−34×1.8×1014 =11.88×10−20J =1.6×10−1911.88×10−20eV =0.74eV
Similarly, EB=0.91eV
As the incident photons have energy greater than EA but less than EB.
So, photoelectrons will be emitted from metal A only