EM Radiation Q: Hydrogen Atom Transitions & Frequency

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Discussion Overview

The discussion revolves around the electromagnetic radiation produced by hot hydrogen gas and its frequency characteristics, particularly in relation to atomic transitions between energy levels. Participants explore concepts related to thermal excitation, photon emission, and the implications of atomic movement on frequency, addressing both theoretical and conceptual aspects of the topic.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants assert that hot hydrogen gas cannot produce a single frequency due to the random excitation of electrons across multiple energy levels, leading to the emission of photons at different frequencies.
  • Others propose that in a theoretical scenario, it might be possible to have a gas emit radiation at a single frequency, but this would require specific conditions that are unlikely in a typical hot gas situation.
  • There is a discussion about the transitions from n=3 to n=2 and n=2 to n=1, with some participants suggesting that the photon emitted from n=2 to n=1 has a higher frequency than that from n=3 to n=2 due to the greater energy difference.
  • Some participants mention the Doppler effect, indicating that the movement of hydrogen atoms could affect the observed frequency of emitted photons, leading to a spread in frequencies.
  • There is contention regarding the relevance of laser-like conditions to the question, with some participants arguing that the original question pertains to thermal excitation rather than laser emissions.

Areas of Agreement / Disagreement

Participants generally agree that hot hydrogen gas does not emit a single frequency due to the nature of thermal excitation. However, there are competing views on the possibility of achieving a single frequency under specific conditions, and the discussion remains unresolved regarding the implications of atomic movement on emitted frequencies.

Contextual Notes

The discussion highlights limitations in assumptions about thermal excitation and the conditions under which specific frequencies might be emitted. The role of the Doppler effect and the nature of atomic transitions are also noted as factors that complicate the analysis.

Who May Find This Useful

This discussion may be of interest to students and educators in physics, particularly those exploring concepts of atomic transitions, electromagnetic radiation, and the effects of temperature and motion on frequency emissions.

vangto
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hi guys, having a bit of trouble answering this physics question. Wondering if any of the experts can help me out.

Can the electromagnetic radiation produced by a hot gas of hydrogen atoms be exactly of one frequency?

not sure if this is true or not. They say also that the atoms make a transition from state n=2 to n=1 and that all atoms are moving.

hope someone can help

oh, a similar question involving state transitions

A hydrogen atom undergoes a transition from the state n=3 to n=2 and then another transition from n=2 to n=1. Two photons are created due to these processes. Which photon has the higher frequency?

any thoughts?
thanks
 
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No, the hot hydrogen gas cannot produce a single frequency. The hydrogen atoms have many energy levels to which electrons are randomly excited by thermal energy. As the electrons decay to lower energy levels, the atom emits photons of different frequencies.

As for the second question, the distance (in energy) between n=1 and n=2 is larger than the distance between any two higher energy levels.

- Warren
 
how does dat explain y it cannot have a frequency of one thou
 
leafvillage said:
how does dat explain y it cannot have a frequency of one thou
The hydrogen atoms have many energy levels to which electrons are randomly excited by thermal energy. Each of these energy levels (transitions from one to another, actually) will result in a photon with a unique frequency. There's no way to make the electrons go into only one energy level with thermal excitation.

- Warren
 
chroot said:
(...) There's no way to make the electrons go into only one energy level with thermal excitation (...)

Warren,u could use another photons :rolleyes: No need to heat the gas...

Daniel.
 
dextercioby said:
Warren,u could use another photons :rolleyes: No need to heat the gas...
Please read the question before responding.

Can the electromagnetic radiation produced by a hot gas of hydrogen atoms be exactly of one frequency?

- Warren
 
dextercioby said:
Warren,u could use another photons :rolleyes: No need to heat the gas...

In theory, you could produce a gas that within a given interval of time, only emitted lines at one transition, but it would either be an extreme statistical improbability, a tiny interval of time, or an extremely contrived situation (say, a near absolute zero gas illuminated with photons of one energy). The questioner used the term "hot" gas, so I think it's fairly natural to assume that they weren't interested in such situations.
 
I just gave a counterexample to your statement...There is "a way to make electrons go into only one energy level with thermal excitation".

I had read the question (and your answer) and i was addressing you...

Daniel.
 
SpaceTiger said:
In theory, you could produce a gas that within a given interval of time, only emitted lines at one transition, but it would either be an extreme statistical improbability, a tiny interval of time, or an extremely contrived situation (say, a near absolute zero gas illuminated with photons of one energy). The questioner used the term "hot" gas, so I think it's fairly natural to assume that they weren't interested in such situations.


I know what the questioner was interested in knowing & i think Warren answered pretty well.He just made an assertion which is not valid.

Daniel.
 
  • #10
The questioner is not asking about lasers, dexter. Drop it.

- Warren
 
  • #11
a little confused

thanks for all the input guys. sorry for posting in two different forums

i'm just a little confused, since the point was brought up that the gas is hot and in this state there is really no chance that the radiation will be of only one frequency

but what is this about lasers? you see these are conceptual homework questions not worth much but are very important in the understanding of this first year physics course, and they seem to throw a lot of trick questions our way.. keeping this in mind, is it still safe to say that the there isn't going to be a single frequency at all for the hot hydrogen atom?

oh and warren also said this
"The hydrogen atoms have many energy levels to which electrons are randomly excited by thermal energy. Each of these energy levels (transitions from one to another, actually) will result in a photon with a unique frequency. There's no way to make the electrons go into only one energy level with thermal excitation."

this can help me with my second question since each transition results in a photon with a unique frequency, and you said the most energetic transition is from n=2 to n=1, does this mean that the photon has a higher frequency at this state or a lower one than from n=3 to n=2.

thanks
 
  • #12
Frequency is proportional to the difference between various energy levels...

Daniel.
 
  • #13
chroot said:
No, the hot hydrogen gas cannot produce a single frequency. The hydrogen atoms have many energy levels to which electrons are randomly excited by thermal energy. As the electrons decay to lower energy levels, the atom emits photons of different frequencies.
But since the question specifies that the hydrogen atoms are moving from n=2 to n=1, doesn't this mean they must emit a single frequency?

If the hydrogen atoms are moving, does this affect the frequency emitted?
 
  • #14
Well,

A real hot gas will not excite JUST the n=2 state. However, if the only state excited were n=2, then the photons would all be the same frequency.

Of course, the Doppler effect would cause a spread in the frequencies as received by a detector, since the atoms are moving around at relatively high speeds.

- Warren
 
  • #15
aluminumboat said:
If the hydrogen atoms are moving, does this affect the frequency emitted?

This has been mentioned several times recently, but it seems worth mentioning this thread again. There are several mechanisms by which lines are broadened, so in practice, things are never emitted all at the exact same frequency, even in a laser.
 

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