The stopping potential in a photoelectric experiment is linearly related to the inverse of the wavelength (1/λ) of the light falling on the cathode. The potential difference inverse of the cut-off wavelength (1/λ) of the X-ray emitted. Show that the slopes of the lines in the two cases are equal and find its value.
Given:
Stopping potential is proportional to inverse of wavelength (1/λ)
let Vo be the stopping potential
v1 and λ1 be the operating frequency and voltage of the x-ray tube
v2 and λ2be the cut- off frequency and voltage of the x-ray tube
since ,
and
in the above equations, slopes are the same
∴V0λ2=Vλ1
Value of the slope= 1.242×10-6 Vm