The electron in a hydrogen atom makes a transition $n_1 \to n_2$,where $n_1$ and $n_2$ are the principal quantum numbers of the two states. Assume the Bohr model to be valid. The time period of the electron in the initial state is eight times that in the final state. The possible values of $n_1$ and $n_2$ are

Minimum excitation potential of Bohr's first orbit in hydrogen atom is.....$V$

The number of de-Broglie wavelengths contained in the second Bohr orbit of a hydrogen atom is

In $Li^{++}$ ion,an electron in the first Bohr orbit is excited to a higher energy level by a radiation of wavelength $\lambda$. When the ion de-excites to the ground state in all possible ways (including intermediate emissions),a total of six spectral lines are observed. What is the value of $\lambda$ in $nm$? (Given: $h = 6.63 \times 10^{-34} \, J \cdot s, c = 3 \times 10^8 \, m/s, 1 \, eV = 1.6 \times 10^{-19} \, J$)

The angular momentum of the orbital electron is an integral multiple of:

The frequency of revolution of an electron in the $n^{\text{th}}$ orbit of a hydrogen atom is