Electrons are emitted from an electron gun at almost zero velocity and are accelerated by an electric filed E through a distance of 1.0 m. The electrons are now scattered by an atomic hydrogen sample in ground state. What should be the minimum value of E so that red light of wavelength 656.3 nm may be emitted by the hydrogen?

Question

Philoid · Accepted Answer

As the red light has wavelength 656.3nm which is in Balmer Series so for minimum energy change in state should be from n=2 to n=3. But right now hydrogen atom is in ground state.

Hence n=1 to n=3

So

Hence minimum electric field required = 12.09 v/m