Question:
Consider a thin target (10–2m square, 10–3m thickness) of sodium, which produces a photocurrent of 100µA when a light of intensity 100W/m2 (λ = 660nm) falls
on it. Find the probability that a photoelectron is produced when a photon strikes a sodium atom. [Take density of Na = 0.97 kg/m3].
Solution:
Area = 10-4 m2
Thickness = 10-3 m
Current = 10-4 A
Intensity = 100 W/m2
Mass = (volume)(density) = 0.97 × 10-4 gm
No.of target atoms = 0.254 × 1019
Total energy = nhv
Where n = 3.3 × 1016
The probability of emission of photoelectrons is 7.5 × 10-21