The electron in the hydrogen atom jumps from excited state (n=3) to its ground state (n=1) and the photons thus emitted irradiate a photosensitive…

The electron in the hydrogen atom jumps from excited state $\displaystyle (n=3)$ to its ground state $\displaystyle (n=1)$ and the photons thus emitted irradiate a photosensitive material. If the work function of the material is $\displaystyle 5.1$ eV, the stopping potential is estimated to be (the energy of the electron in $\displaystyle n^{\text {th }}$ state $$\left.E_n=-\frac{13.6}{n^2} e V\right) $$