The stopping potential for the photoelectrons emitted from a metal surface of work function 1.7 eV is 10.4 V. Find the wavelength of the radiation used. Also, identify the energy levels in hydrogen atom, which will emit this wavelength.

Explanation

`phi=1.7 eV, V_(s)=10.4 V, K_(max) =eV_(s)=10.4 eV`
`E=phi+K_(max)=1.7+10.4=12.1 eV`
`lambda=(1242)/(E(eV))nm=(1242)/(12.1)=102.6 nm`
The energy difference 12.1 eV corresponds to n=3 to n=1