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I am confused, how can hydrogen produce emission lines in the visible light region? the only excitation that can happen to hydrogen is from energy level 1 to any other energy level, all of that correspond to ultraviolet range.

This can happen if the electron of the hydrogen atom can be excited from energy level 1 to 2 then instantly from 2 to any other level. But, I read before that the electron can't have double excitation.

Also, this can happen if the hydrogen is ionised, then the free electron is the one which produced the visible light spectrum.

What is right?

Mohamed Ayman
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    The "production" of light happens when an electron de-excites. It emits a photon. Upon excitation, it absorbs a photon. – Peeyush Kushwaha Mar 21 '16 at 20:51
  • yes, I know. the energy of the emitted photon is the same as the absorbed one. – Mohamed Ayman Mar 21 '16 at 20:52
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    So visible light is produced when electrons come from a higher level of excitation down to level 2. See Balmer Series on wikipedia – Peeyush Kushwaha Mar 21 '16 at 20:57
  • my question is how come.it's excited in the first place? there is no excitation from energy level 1 in hydrogen that have the energy of visible light – Mohamed Ayman Mar 21 '16 at 20:59
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    Your assertion that "the energy of the emitted photon is the same as the absorbed one" is misleading. The electron may be excited from 1 to 3, then de-excited from 3 to 2 (giving off red) and then from 2 to 1. – Peeyush Kushwaha Mar 21 '16 at 21:04
  • oh, Really? I didn't know that. is there a resource where i can make sure that this statement is true? – Mohamed Ayman Mar 21 '16 at 21:05
  • thanks alot.. i consulted wikipedia and it said " After excitation the atom may return to the ground state or a lower excited state, by emitting a photon with a characteristic energy." thanks again for help. – Mohamed Ayman Mar 21 '16 at 21:08
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    http://hyperphysics.phy-astr.gsu.edu/hbase/hyde.html#c4 – Gert Mar 21 '16 at 22:01
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    Only the excitations of ground state hydrogen are restricted to the ultraviolet. Likewise de-excitation ending in the ground state *are in the ultraviolet. – dmckee --- ex-moderator kitten Mar 21 '16 at 22:21
  • (+1) I answer your question here: https://physics.stackexchange.com/a/768678/313612. The electrically energized tube has both hydrogen molecules and hydrogen atoms that came from hydrogen molecules that were dissociated, i.e., broken into atoms. Some of the atoms are excited and de-excite by emitting the characteristic hydrogen atomic emission lines, e.g., the Balmer series that I show. And likewise, some excited hydrogen molecules emit light, e.g., the Fulcher alpha bands. – Ed V Jul 20 '23 at 13:13

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