Question

The graphs below show the variation of the stopping potential V_S with the frequency (ν) of the incident radiations for two different photosensitive materials M₁ and M_2.

Express work function for M₁ and M₂ in terms of Planck’s constant(h) and Threshold frequency and charge of the electron (e).

If the values of stopping potential for M₁ and M₂ are V₁ and V₂ respectively then show that the slope of the lines equals to `(V_1-V_2)/(V_(01)-V_(02))` for a frequency,

ν > ν₀₂ and also ν > ν₀₁

Answer 1

`"W"_(01) = ("h"ν_(01))/"e" and "W"_(02) = ("h"ν_(02))/"e"`

`"V"_1 = ["h"/"e"] ν-["h"/"e"]"V"_01`

`"V"_2 = ["h"/"e"]ν-["h"/"e"]"V"_(02)`

∴ `"V"1 - "V"2 = ["h"/"e"]("V"_(01)-"V"_(02))`

`["h"/"e"] = ("V"1-"V"2)/("V"_(01)-"V"_(02))`