In an experiment

Photoelectric equation

eV₀ = hv - ϕ_{0 …………} eq.01

Where e = Charge on an electron = 1.6 × 10^-19 C

V₀ = Stopping Potential

h = plank’s constant

v = frequency of photon

ϕ₀ = Work function of the metal

Rewriting equation no. 1

V₀ = hv/e - ϕ₀/e ………………………………equ.02

h/e is slop of the line represented by above equation02.

Therefore h/e = slop of the line = 4.12 × 10^-15 Vs

h = 1.6 × 10^-19 × 4.12 × 10^-15 = 6.594 × 10^-34 Js

Value of plank’s constant ‘h’ from above experiment is equal to 6.594 × 10^-34 Js.