Comparing Emission Spectrum of Moving & Stationary Hydrogen

In summary, the question is about how the frequencies of spectral lines from a moving source of hydrogen gas would differ from those observed in a laboratory on Earth. The answer involves the concept of redshift and the Doppler effect, where the moving source causes a decrease in frequency and an increase in wavelength. The type of gas being observed does not affect this phenomenon.
  • #1
Bradracer18
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Homework Statement



Ok guys, Helping my girlfriend out once again. She(if you haven't seen this before) is in Physics 101...yet, I(have taken all engineering courses) can't figure these out. Their book is absolutely terrible! Please give an answer that I can understand(as I like to learn too)...and one also that I can explain to her, so she will understand. I appreciate the help!

If an astronomer examines the emission spectrum from luminous hydrogen gas that is moving away from he Earth at a high speed and compares it to a spectrum of hydrogen seen in a laboratory on Earth, what would be different about the frequencies of aspectral lines from the two sources?

I don't have any clue as to the answer. Thanks again guys!

Homework Equations





The Attempt at a Solution

 
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  • #2
Can anyone help me with this...I just plain and simple do NOT understand it well enough to explain it to her.

Or possibly you could show me a website where I could read up on the material, and try to learn the answer...??...
 
  • #3
You'll want to research redshift and blueshift; google should suffice to find some decent sources.
 
  • #4
Google "Doppler effect".
 
  • #5
Ok, well I've searched basically both of those things.

I came up with this conclusion:

Due to the fact that the spectrum is moving AWAY from the Earth, it will cause a "redshift". This redshift, increases wavelength which also corresponds to a decrease in the frequency of the electromagnetic radiation.

Is that correct? Also, is that correct with the hydrogen gas(or does the gas not really matter, in this case)?

So basically, I guess I'm saying that the one going away from Earth will have a lower frequency than the one observed in the lab.
 
  • #6
Yes, that's correct. And the fact it's hydrogen doesn't really matter.
 

1. What is the emission spectrum of hydrogen?

The emission spectrum of hydrogen is a series of lines observed in the visible, ultraviolet, and infrared regions of the electromagnetic spectrum. These lines are the result of photons being emitted when electrons in a hydrogen atom transition from higher energy levels to lower energy levels.

2. How does the emission spectrum of moving hydrogen differ from stationary hydrogen?

The emission spectrum of moving hydrogen appears to be shifted towards longer wavelengths compared to the spectrum of stationary hydrogen. This is known as the Doppler effect, where the motion of the hydrogen atoms causes a change in the frequency of the emitted photons.

3. What causes the Doppler effect in the emission spectrum of moving hydrogen?

The Doppler effect is caused by the relative motion between the observer and the source of the light. In the case of moving hydrogen, the observer is the scientist measuring the emission spectrum, and the source of the light is the hydrogen atoms moving towards or away from the observer.

4. How does the speed of the hydrogen atoms affect the emission spectrum?

The speed of the hydrogen atoms affects the emission spectrum by causing a shift in the wavelength of the emitted photons. As the speed of the hydrogen atoms increases, the shift towards longer wavelengths becomes more prominent.

5. Why is it important to compare the emission spectrum of moving and stationary hydrogen?

Comparing the emission spectrum of moving and stationary hydrogen allows scientists to study the effects of the Doppler effect and understand how the motion of atoms can impact the observed spectrum. This is valuable in a variety of scientific fields, such as astrophysics and spectroscopy, where the Doppler effect is commonly observed.

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