The Bohr model for the H-atom relies on the Coulomb's law of electrostatics. Coulomb's law has not directly been verified for very short distances of the order of angstroms. Supposing Coulomb's law between two opposite charge $+q_1,-q_2$ is modified to
$$\begin{aligned} |\mathbf{F}| & =\frac{q_1 q_2}{\left(4 \pi \varepsilon_0\right)} \frac{1}{r^2}, r \geq R_0 \\ & =\frac{q_1 q_2}{4 \pi \varepsilon_0} \frac{1}{R_0^2}\left(\frac{R_0}{r}\right)^{\varepsilon}, r \leq R_0 \end{aligned}$$
Calculate in such a case, the ground state energy of a H -atom, if $E=0.1$, $R_0=1 \mathop A\limits^o$.
Considering the case, when $r \leq R_0=1 \mathop A\limits^o$
$$\begin{aligned} & \text { Let } \varepsilon=2+\delta \\ & F=\frac{q_1 q_2}{4 \pi \varepsilon_0} \cdot \frac{R_0^\delta}{r^{2+\delta}} \end{aligned}$$
where,
$$\begin{aligned} \frac{q_1 q_2}{4 \pi_0 \varepsilon_0} & =\left(1.6 \times 10^{-19}\right)^2 \times 9 \times 10^9 \\ & =23.04 \times 10^{-29} \mathrm{~N} \mathrm{~m}^2 \end{aligned}$$
The electrostatic force of attraction between positively charged nucleus and negatively charged electrons (Coulombian force) provides necessary centripetal force.
$$\begin{aligned} & =\frac{m v^2}{r} \quad \text { or } \quad v^2=\frac{\wedge R_0^\delta}{m r^{1+\delta}} \quad\text{.... (i)}\\ m v r & =n h \cdot r=\frac{n \hbar}{m v}=\frac{n h}{m}\left[\frac{m}{\wedge R_0^\delta}\right]^{1 / 2} r^{1 / 2+\delta / 2}\quad \text{[Applying Bohr's second postulates]} \end{aligned}$$
Solving this for $r$, we get $\quad r_n=\left[\frac{n^2 \hbar^2}{m \wedge R_0^\delta}\right]^{\frac{1}{1-\delta}}$ where, $r_n$ is radius of $n$th orbit of electron.
For $n=1$ and substituting the values of constant, we get
$$\begin{aligned} r_1 & =\left[\frac{\hbar^2}{m \wedge R_0^\delta}\right]^{\frac{1}{1-\delta}} \\ r_1 & =\left[\frac{1.05^2 \times 10^{-68}}{9.1 \times 10^{-31} \times 2.3 \times 10^{-28} \times 10^{+19}}\right]^{\frac{1}{2.9}} \\ & =8 \times 10^{-11} \\ & =0.08 \mathrm{~nm}\quad (< 0.1 \text{nm}) \end{aligned}$$
This is the radius of orbit of electron in ground state of hydrogen atom.
$$\begin{aligned} v_n & =\frac{n \hbar}{m r_n}=n \hbar\left(\frac{m \wedge R_0^\delta}{n^2 \hbar^2}\right)^{\frac{1}{1-\delta}} \\ \text { For } n & =1, v_1-\frac{\hbar}{m r_1}=1.44 \times 10^6 \mathrm{~m} / \mathrm{s} \end{aligned}$$
[This is the speed of electron in ground state]
$$\begin{aligned} &\mathrm{KE}=\frac{1}{2} m v_1^2-9.43 \times 10^{-19} \mathrm{~J}=5.9 \mathrm{eV}\\ &\text { [This is the KE of electron in ground state] } \end{aligned}$$
PE till $R_0=-\frac{\Lambda}{R_0}$ [This is the PE of electron in ground state at $r=R_0$ ]
PE from $R_0$ to $r=+\wedge R_0^\delta \int_{R_0}^r \frac{d r}{r^{2+\delta}}=+\frac{\wedge R_0^\delta}{-1-\delta}\left[\frac{1}{r^{1+\delta}}\right]_{R_0}^r$
[This is the PE of electron in ground state at $R_0$ to $r$ ]
$$\begin{aligned} & =-\frac{\wedge R_0^\delta}{1+\delta}\left[\frac{1}{r^{1+\delta}}-\frac{1}{R_0^{1+\delta}}\right]=-\frac{\Lambda}{1+\delta}\left[\frac{R_0^\delta}{r^{1+\delta}}-\frac{1}{R_0}\right] \\ P E & =-\frac{\Lambda}{1+\delta}\left[\frac{R_0^\delta}{r^{1+\delta}}-\frac{1}{R_0}+\frac{1+\delta}{R_0}\right] \\ P E & =-\frac{\Lambda}{-0.9}\left[\frac{R_0^{-1.9}}{r^{-0.9}}-\frac{1.9}{R_0}\right] \\ & =\frac{2.3}{0.9} \times 10^{-18}\left[(0.8)^{0.9}-1.9\right] \mathrm{J}=-17.3 \mathrm{̃eV} \end{aligned}$$
Total energy is $(-17.3+5.9)=-11.4 \mathrm{eV}$
This is the required TE of electron in ground state.