The radius of the first Bohr orbit of a hydrogen atom is $0.53 \times 10^{-8} \ cm$. The velocity of the electron in the first Bohr orbit is

When an electron with energy $10.8 \,eV$ collides with a hydrogen $(H)$ atom,what will happen?

Light of frequency $1.6 \times 10^{16} \ Hz$ falling on a metal plate emits electrons that have double the kinetic energy compared to the kinetic energy of electrons emitted when light of frequency $1.0 \times 10^{16} \ Hz$ falls on the same plate. The threshold frequency $(v_0)$ of the metal in $Hz$ is:

Wave number of a spectral line for a given transition is $y \ cm^{-1}$ for $He^{+}$,then its value for $Li^{2+}$ for the same transition is

The ratio of energy of a hydrogen atom for the first and second excited states is ......

The energy of an electron revolving in the $n^{th}$ Bohr's orbit of an atom is given by the expression