Question -
Answer -
Intensity of incident light, I =10−5 W m−2
Surface area of a sodium photocell, A =2 cm2 = 2 × 10−4 m2
Incident power of the light, P = I ×A
= 10−5 × 2 × 10−4
= 2 × 10−9 W
Workfunction of the metal,
= 2 eV= 2 × 1.6 × 10−19
= 3.2 × 10−19 J
Number of layers of sodium that absorbs theincident energy, n = 5
We know that the effective atomic area of asodium atom, Ae is 10−20 m2.
Hence, the number of conduction electronsin n layers is given as:
The incident power isuniformly absorbed by all the electrons continuously. Hence, the amount ofenergy absorbed per second per electron is:
Time required forphotoelectric emission:
Thetime required for the photoelectric emission is nearly half a year, which isnot practical. Hence, the wave picture is in disagreement with the givenexperiment.