In Bohr's model of hydrogen atom, find the percentage change in the radius of its orbit when an electron makes a transition from n =3 state to n =2…

$\displaystyle r \propto n^{2}$ $\displaystyle \frac{r_{2}}{r_{3}}=\frac{4}{9}$ Percentage change when electron makes transition from $\displaystyle n=3$ to $\displaystyle n=2$: $\displaystyle =\frac{r_{2}-r_{3}}{r_{3}} \times 100$ $\displaystyle =\left(\frac{4-9}{9}\right) \times 100$ $\displaystyle =55.55 \%$