What is the wavelength of light emitted when the electron in a hydrogen atom undergoes transition from an energy level with n = 4 to an energy level with n = 2

Explanation

`bar(v) = (1)/(lambda) = R_(H)[(1)/(n_(1)^(2)) - (1)/(n_(2)^(2))] rArr bar(v) = 109677[(1)/(2^(2)) - (1)/(4^(2))]`
`bar(v) = 20564.5 cm^(-1) rArr lambda = 4.862 xx 10^(-5) cm`