Question

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?

Answer 1

10^-8 = A°
if you want to answer in A°
then 4862A°

Answer 2

According to Balmer formula

Wave no = RH [1/n12 – 1/n22]

Here n1 = 2 ,       n2 = 4,     RH = 109678

Putting these values in the equation we get

Wave number =109678(1/22 - ¼2) = 109678 x 3/16

Also λ = 1/ wave number

Therefore λ = 16 / 109678 x 3 = 486 nm