In Bohr's model of the hydrogen atom,the ratio between the period of revolution of an electron in the orbit of $n=1$ to the period of revolution of the electron in the orbit $n=2$ is

Ratio of centripetal acceleration for an electron revolving in $3^{\text{rd}}$ and $5^{\text{th}}$ Bohr orbit of hydrogen atom is

An electron is revolving in $n = 3$ orbit. What will be the magnetic field at the centre of the hydrogen atom? (in $T$)

The $21\, cm$ radio wave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction in atomic hydrogen. The energy of the emitted wave is nearly

The wavelength of light emitted when an electron transitions from the second orbit to the first orbit in a hydrogen atom is:

An electron is revolving in a circular orbit of radius '$r$' in a hydrogen atom. Using Bohr's theory, the angular momentum of the electron is (where '$M$' = magnetic dipole moment,'$m$' = mass of electron,'$e$' = charge of electron).