Question

A single electron orbits a stationary nucleus of charge +Ze, where Z is a constant. It requires $47.2$eV to excite an electron from second Bohr orbit, find the value of Z.

Answer 1

Stationary nucleus of charge $+Ze$.

Energy=$\mathrm{13.6.}\frac{z^2}{n^2}$

$13.6\times \frac{2^2}{2^2}=47.2$

$z^2=\frac{47.2\times 4}{13.6}$

$z=4$