Electrons with maximum kinetic energy 3eV are ejected from a metla surface by ultraviolet radiation of wavelength `1500Å`. Determine the work function of the metal, the threshold wavelength of metal and the stopping potential difference required to stoop the emission of electrons.

Explanation

Energy of incident photon in eV is
`= E = ( 12431) /( 1500) eV`
According to photon electric effect equation,we have
`E - phi+ KE_("max") rArr ` or` phi- E- KE_("max")`
`= 8.29 - 3 eV ` or ` = 5.29 eV`
Threshold wavelength for the metal surface corresponding to work function 5.29eV is given as
`lambda_(th) = ( 12431)/( 5.29)Å= 2349.9 Å`
Stopping potential for the ejected electrons can be given as
`V_(0) + ( KE_("max"))/( e ) = ( 3eV)/( e) =3` volt