The energy of a hydrogen atom in its ground state is $-13.6 \ eV$. The energy of the level corresponding to the quantum number $n = 2$ (first excited state) in the hydrogen atom is......$eV$.

The total energy of an electron in an orbit of a hydrogen atom is $E$. The potential energy of the electron in the same orbit is:

An electron collides elastically with an $H$-like atom and excites it from the ground state to $n = 3$. Find the energy transferred to the $H$-like atom in $eV$.

The kinetic energy of an electron in the $n^{th}$ orbit of a hydrogen-like species with atomic number $Z$ is $13.6 \frac{Z^2}{n^2} \ eV$. The potential energy of this electron in the same orbit will be:

The ground state energy of the hydrogen atom is $-13.6 \ eV$. The kinetic and potential energy of the electron in the second excited state are,respectively:

The figure shows the energy levels of a certain atom. When the electron de-excites from $3E$ to $E$,an electromagnetic wave of wavelength $\lambda$ is emitted. What is the wavelength of the electromagnetic wave emitted when the electron de-excites from $\frac{5E}{3}$ to $E$?