Find the wavelength in a hydrogen spectrum between the range `500nm to 700nm`

Explanation

`(hc)/(lambda)= (1242eV nm)/(500nm) = 2.44 ev`
The energy of a photon of wavelength `700nm`is
`(hc)/(lambda) = (1242ev nm)/(700 nm) = 1.77eV`
The energy difference between the static involved in the `2.44eV`

some of the energy of hydrogen static It is clear that only these transition which and at `n = 2` may emit photon of energy of the photon of energy between `1.77eV and 2.44eV` out of these only `n =3 rarr n = 2` fall in the proper range The energy of the photon emitted in the transition `n = 3 to n = 2 is Delta E = (3.4 - 1.5)eV= 1.9eV` The wavelength is
`lambda = (hc)/(Delta E)`
= (1242eV nm)/(1.8eV) = 654 nm`