The ratio of the ionization energy of a Bohr's hydrogen atom to that of a Bohr's hydrogen-like lithium atom is:

In a hydrogen atom,the binding energy of the electron in the $n^{th}$ state is $E_n$. Then,the frequency of revolution of the electron in the $n^{th}$ orbit is:

$A$ hydrogen atom in an excited state transitions to the ground state by emitting a photon of wavelength $\lambda$. The value of the principal quantum number $n$ of the excited state is:
($R$: Rydberg constant)

In a hydrogen atom,find the magnetic field at the center in the ground state. Given that Bohr's radius is $r_{0} = 5 \times 10^{-11} \, m$ (in $T$).

Show that the first few frequencies of light that is emitted when electrons fall to the $n^{\text{th}}$ level from levels higher than $n$,are approximate harmonics (i.e.,in the ratio $1:2:3...$) when $n >> 1$.

If an electron is moving in the $n^{\text{th}}$ orbit of the hydrogen atom,then its velocity $(v_n)$ for the $n^{\text{th}}$ orbit is given as: