Question -
Answer -
Intensity of incident light,┬аI┬а=10тИТ5┬аW mтИТ2
Surface area of a sodium photocell,┬аA┬а=2 cm2┬а= 2 ├Ч 10тИТ4┬аm2
Incident power of the light,┬аP = I ├ЧA
= 10тИТ5┬а├Ч 2 ├Ч 10тИТ4
= 2 ├Ч 10тИТ9┬аW
Workfunction of the metal,
┬а= 2 eV= 2 ├Ч 1.6 ├Ч 10тИТ19
= 3.2 ├Ч 10тИТ19┬аJ
Number of layers of sodium that absorbs theincident energy,┬аn┬а= 5
We know that the effective atomic area of asodium atom,┬аAe┬аis 10тИТ20┬аm2.
Hence, the number of conduction electronsin┬аn┬аlayers 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.