# EM Radiation Q: Hydrogen Atom Transitions & Frequency

• vangto
In summary: However, in a sufficiently narrow frequency interval you might be able to say that there is no frequency variation, so I suppose that the answer to your question is "yes", but I don't know what it would be used for.In summary, the hot gas of hydrogen atoms cannot produce a single frequency as there are multiple energy levels to which electrons are excited and decay to, resulting in photons of different frequencies. Even if the hot gas only excited the n=2 state, the Doppler effect from the atoms' movement would cause a spread in frequencies. However, in a narrow frequency interval, it could be possible to see no frequency variation.
vangto
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

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 No need to heat the gas...

Daniel.

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

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 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".

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.

The questioner is not asking about lasers, dexter. Drop it.

- Warren

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

Frequency is proportional to the difference between various energy levels...

Daniel.

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?

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

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.

## 1. What is EM radiation?

EM radiation, also known as electromagnetic radiation, is a form of energy that is emitted and absorbed by charged particles. It includes a wide range of wavelengths, from radio waves to gamma rays.

## 2. How are hydrogen atom transitions related to EM radiation?

Hydrogen atom transitions refer to the movement of an electron between different energy levels in a hydrogen atom. When this happens, EM radiation is emitted or absorbed, depending on the direction of the transition.

## 3. What is the frequency of EM radiation emitted during a hydrogen atom transition?

The frequency of EM radiation emitted during a hydrogen atom transition is determined by the difference in energy between the two energy levels involved. This frequency can be calculated using the Rydberg formula.

## 4. Why is the study of hydrogen atom transitions important?

Studying hydrogen atom transitions allows scientists to understand the behavior of atoms and the properties of EM radiation. It also has practical applications, such as in the development of atomic clocks and laser technology.

## 5. How does EM radiation interact with matter during a hydrogen atom transition?

During a hydrogen atom transition, EM radiation can be either absorbed or emitted by matter. The amount of energy absorbed or emitted depends on the frequency of the radiation and the properties of the matter.

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