In a photoelectric experiment ultraviolet light of wavelength \(280 nm\) is used with lithium cathode having work functi…

In a photoelectric experiment ultraviolet light of wavelength \(280 nm\) is used with lithium cathode having work function \(\phi=2.5 eV\). If the wavelength of incident light is switched to \(400 nm\), find out the change in the stopping potential. \(\left(h=6.63 \times 10^{-34} Js , c=3 \times 10^8 ms ^{-1}\right)\)