Question

calculate the wavelength (in nm) of a spectral line produced in the hydrogen spectrum, when an electron falls from the 4th energy level to the 2nd energy level. Which region of the electromagnetic spectrum does this spectral line belong to?

Answer 1

According to the Balmer's formula, the wavelength of the electronic transition from the 4^th energy level to the 2^nd energy level is:

$\lambda = B\frac{4^2}{4^2-2^2}$ ,

where $B$ is a constant, equal to 364.50682 nm.

$\lambda = 364.50682\frac{16}{12} = 486$ nm.

This spectral line belongs to the visible region (390-750 nm) and has brilliant bluish green color.