The distance between two successive orbits of H-atom is

General formula of radius of an orbit:

$\mathrm{r}=\frac{{\mathrm{r}}_{\circ }{\mathrm{n}}_2}{\mathrm{Z}}$

Here, the value of r_o is $0.529 \stackrel{\circ }{\mathrm{A}.}$

Assume that the value of n for the first energy level is n₁ and the second energy level is n₂. Distance between them is calculated as:

$$\begin{gathered} \mathrm{distance}={\mathrm{r}}_2-{\mathrm{r}}_1 \\ =\frac{{\mathrm{r}}_{\circ }{\mathrm{n}}_2^2}{\mathrm{Z}}-\frac{{\mathrm{r}}_{\circ }{\mathrm{n}}_1^2}{\mathrm{Z}} (\mathrm{Z}=1 \mathrm{for} \mathrm{H}-\mathrm{atom}) \\ =0.529 \stackrel{\circ }{\mathrm{A} }\left[{\mathrm{n}}_2^2-{\mathrm{n}}_1^2\right] \end{gathered}$$