Whenever an electron jumps from outer stationary orbit to inner stationary orbit then a

Derive an expression for the wavelength of spectral line when an electron jumps from higher stationary orbit to lower stationary orbit.

The wavelength of a spectral line emitted due to the transition of electron from outer stationary orbit to inner stationary orbit is given by

what is a stationary orbit ?

What are stationary orbits?

In Bohr’s stationary orbits