Silver has a work function of 4.7 eV . When ultraviolet light of wavelength 100 nm is incident on it a potential of 7.7 V is required to stop the photoelectrons from reaching the collector plate. How

Question

Silver has a work function of 4.7 eV . When ultraviolet light of wavelength 100 nm is incident on it a potential of 7.7 V is required to stop the photoelectrons from reaching the collector plate. How much potential will be required to stop photoelectrons, when light of wavelength 200 nm is incident on it?

TestHub · Accepted Answer

From Einstein's Photoelectric equation, ev 0 ​ + ϕ = λ hc ​ and ev 0 ​ + ϕ 0 ​ = λ ′ hc ​ eV 0 ​ + ϕ ev 0 ′ ​ + ϕ ​ = λ ′ λ ​ = 200 100 ​ = 2 1 ​ 2 ev 0 ′ ​ + 2 ϕ = ev 0 ​ + ϕ ev 0 ′ ​ = 2 ev 0 ​ − ϕ ​ = 2 7.7 − 4.7 ​ = 1.5 V ​

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