According to Bohr's theory,the radius of an electron in an orbit described by principal quantum number $n$ and atomic number $Z$ is proportional to:

The wavelength of the energy emitted when an electron transitions from the fourth orbit to the second orbit in a hydrogen atom is $20.397 \, cm$. The wavelength of the energy for the same transition in $He^+$ is .......... $cm$.

De-Broglie wavelength of an electron orbiting in the $n=2$ state of a hydrogen atom is close to (Given Bohr radius $= 0.052 \ nm$) (in $nm$)

When an electron jumps from the $n = 4$ level to the $n = 1$ level,the angular momentum of the electron changes by:

If an electron is moving in the $n^{\text{th}}$ orbit of the hydrogen atom,then its velocity $(v_n)$ for the $n^{\text{th}}$ orbit is given as:

In a hydrogen atom,an electron transitions from an orbit of radius $R$ to an orbit of radius $4R$. What is the ratio of their time periods?