de Broglie's Explanation of Bohr's Second Postulate

Bohr's model is unable to explain the relative intensities of the frequencies in the spectrum.

The Bohr model is applicable to hydrogenic atoms.

In a hydrogen atom an electron is moving in the $n^{th}$ orbit of radius $r_n$. the de broglie wavelength associated with this electron is $\frac{n}{2{\mathrm{\pi r}}_{\mathrm{n}}}$.

De-Broglie wavelength of a body of mass m and kinetic energy E is given by (symbols have their usual meanings):

If the radius of the first Bohr orbit is $x$, then de-Broglie wavelength of electron in $3^{\mathrm{rd}}$ orbit is nearly

The ratio of the de-Broglie wavelength of an $\alpha$-particle and a proton of same kinetic energy is

The de-Broglie wavelength of an electron in the ground state of the hydrogen atom is