Question

Write Einstein's photoelectric equations and point out any two characteristic properties of photons on which this equations is based.
Briefly explain the three observed features which can be explained by this caution.

Answer 1

Einstein's photoelectric effect equations:

$h\nu ={\varphi }_0+K.E.$
Where $h\to$Planck's constant
$\nu \to$frequency of the incoming photons
${\varphi }_0\to$work functions of the material and
$KE\to$ Kinetic energy
The two characteristic properties of photons on which this equations is based are as follows:
(i) Photons have particle characteristics, It is emitted or absorbed in units called quanta of lights
(ii) Photons have wave characteristic.It travels in space with particular frequency, a characteristic of waves.
Three observed features which can be explained by this equations are:
(i) Solar cells-Also called photo -voltaic cells. It converts solar radiations to electrical emf
(ii) Television telecast -The dark and bright light part of images are interpreted as high and low electrical charges as given by photoelectric emission principle. These are further processed and transmitted
(iii) Burglar alarm- The moment the ultraviolet radiations is cut due to theif, it stops the supply of photons and thus works as "off" mode and the bell rings automatically