If an electrons jumps from `m^(th)` orbit to the nth orbit `(mgtn)` the energy of the atom changes from `E_(m)` . This extra energy `E_(m)-E_(n)` is emitted as a photon whose wavelength is given by `1/lambda=RZ^(2)(1/n^(2)-1/m^(2))` Where `R=1.09xx10^(7)m^(-1)` (Rydberg constant) A photon ejected from the transition of electron from m^(th) excited state of `He^(+)` ion to `n^(th)` state is allowed to fall on a photoelectric material with work function,`phi=7eV.` [Given `h=4.14xx10^(-15)eVs` and `c=3xx10^(8)ms_(1)]`
The stopping potential for the photon-element ejected due to transition from `2^(nd)` orbit to ground state is

Options

A. `30.5V`
B. `40.5`
C. `50.5V`
D. `60.5V`

Answer

B

Explanation

Stopping potential =`(hc)/e(1/lambda)-phi/e=1/e((hc)/lambda-phi)=40.5V`