From the photoelectric equation,
eV0=λhc−ϕ
Using this equation for the given two cases,
eV1=280nmhc−ϕ
eV2=400nmhc−ϕ
On subtracting,
e(V1−V2)=1240(280×400120)=1.3eV
⇒(V1−V2)=1.3V
In a photoelectric experiment, ultraviolet light of wavelength 280nm is used with lithium cathode having work function ϕ=2.5eV. If the wavelength of incident light is switched to 400nm, find out the change in the stopping potential.
(h=6.63×10−34Js,c=3×108ms−1)
Held on 26 Aug 2021 · Verified 6 Jul 2026.
1.1V
0.6V
1.3V
1.9V
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