The wavelength of the spectral line when the electron is the hydrogen atom undergoes a transition from the energy level `4` to energy level `2` is.

Options

A. 486 nm
B. 486 m
C. `486 Å`
D. 486 cm

Answer

A

Explanation

(a) According to Rydberg equation,
`(1)/(lamda) = R((1)/(x^2) - (1)/(y^2))`
`R = 109678 cm^-1 , x = 2 , y = 4`
`(1)/(lamda) = 109678 [(1)/(4) - (1)/(16)] = 109678 xx (3)/(16)`
On solving, `lamda = 486 nm`.