In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be 4.12 × 10⁻¹⁵ V s. Calculate the value of Planck’s constant

The slope of the cut-off voltage (V) versus frequency (v) of an incident light is given as:

v/v = 4.12 x 10^-15 Vs

V is related to frequency by the equation hv = eV

Where, e = Charge on an electron = 1.6 x 10^-19 C and

h = Planck’s constant Therefore, h = e x (v/v)= 1.6 x 10^-19 x 4.12 x 10^–15 = 6.592 x 10^–34 Js

Hence ,the value of Plank’s constant is 6.592 x 10^–34 Js