Radiation corresponding to the transition n=4 to n=2 in hydrogen atoms falls on a certain metal (work function=2.5 eV). The maximum kinetic energy of the photo-electrons will be:

Options

A. `0.55 eV`
B. `2.55 eV`
C. `4.45 eV`
D. None of these

Answer

4

Explanation

`E_(n)=-13.6/n^(2) eV, E_(2)=13.6/2^(2)`
`E_(4)=-13.6/4^(2)eV//atom`
DeltaE=E_(4)-E_(2)=2.55 eV`
Absorbed energy = work function of metal `+K.E. 2.55=2.5+K.E., K.E.=0.05 eV`