JEE Main 201912 Apr, Morning shiftPhysicsMediumAtoms and Nuclei183× since 2002
An excited He⁺
ion emits two photons in succession, with wavelengths 108.5 nm and 30.4 nm, in making a
transition to ground state. The quantum number n, corresponding to its initial excited state is (for photon of
wavelength , energy ) :