The The work function for a metal is 4 ev. to eject the photoelectrons with zero velocity the wavelength of the incident light should be
We know that E or Φ = h ν Φ is work function of metal
So , h ν = h c / λ
Thus , λ = h c / Φ { since h c is nearly equal to 1240 eV - nm }
=> λ = ( 1240 eV - nm / 4 eV )
=> λ = 310 nm
wavelength of incident light is 310 nm or 3100 Å
So , h ν = h c / λ
Thus , λ = h c / Φ { since h c is nearly equal to 1240 eV - nm }
=> λ = ( 1240 eV - nm / 4 eV )
=> λ = 310 nm
wavelength of incident light is 310 nm or 3100 Å