Where,
V0 = Stopping potential
h = Planck’s constant
e = Charge on an electron
ν = Frequency of radiation
= Work function of amaterial
It can be concluded from equation (1) thatpotential V0 is directly proportional tofrequency ν.
Frequency is also given bythe relation:
This relation can be usedto obtain the frequencies of the various lines of the given wavelengths.
Thegiven quantities can be listed in tabular form as:
| Frequency × 1014 Hz | 8.219 | 7.412 | 6.884 | 5.493 | 4.343 |
| Stopping potential V0 | 1.28 | 0.95 | 0.74 | 0.16 | 0 |
The following figure shows a graphbetween νand V0.
It can be observed that the obtained curveis a straight line. It intersects the ν-axis at 5 × 1014 Hz,which is the threshold frequency (ν0) of the material. PointD corresponds to a frequency less than the threshold frequency. Hence, there isno photoelectric emission for the λ5 line, andtherefore, no stopping voltage is required to stop the current.
Slopeof the straight line = 
From equation (1), the slope 
can be written as:
The work function of themetal is given as:
= hν0
= 6.573 × 10−34 × 5 × 1014
= 3.286 × 10−19 J
=2.054 eV