Ionisation potential of hydrogen atom is ` 13 . 6 eV`. Hydrogen atom in the ground state is excited by monochromatic light fo energy ` 12. 1 eV` . The spectral lines emitted by hydrogen according to Bohr`s theory will be.

Answer

3

Explanation

`E_n = -13. 6 + 12. 1 =- 1.5 eV`
` :. N^2 = E_1 /E_n = ( 13.6)/( 1.5) =9`
` n=3`
Thus transiton occurs from ` 3rd` to `1st` orbit ltbRgt ` :.` Spectral lines emitted ` = sum Delta n = sum (3 - 1)`
` = sum 2 = 1 + 2 = 3` .