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

`"Given "=n_(1)=2, n_(2)=4`, we have
`bar(v)=(1)/(lambda)=R_(H)[(1)/(n_(1)^(2))-(1)/(n_(2)^(2))]rArr barv=109677[(1)/(2^(2))-(1)/(4^(2))]`
`bar=20564.5cm^(-1)rArr lambda=4.862xx10^(-5)cm`