The energy of a hydrogen atom in the ground state is $-13.6 \, eV$. The energy of the $He^+$ ion in the first excited state will be .... $eV$.

Two electrons are moving in orbits of two hydrogen-like atoms with speeds $3 \times 10^5 \ m/s$ and $2.5 \times 10^5 \ m/s$ respectively. If the radii of these orbits are nearly the same,then the possible order of energy states are . . . . . . respectively.

The ionization potential for the second $He$ electron is ...... $eV$.

Consider an electron revolving in a circular orbit of a hydrogen atom,whose quantum number is $n=2$. The velocity of the electron in that orbit is

The ground state energy of a hydrogen atom is $-13.6 \text{ eV}$. What is the ratio of the kinetic energy to the potential energy of the electron in this state?

According to the classical electromagnetic theory,calculate the initial frequency of the light emitted by the electron revolving around a proton in a hydrogen atom.