Cosmic microwave background radiation

In summary, the conversation discussed the cosmic microwave background radiation and its blackbody type spectrum. Using the Wien Law displacemente and a temperature of 2.725 K, the maximum wavelength and frequency of the radiation were determined to be 1.06mm and 2.83E11HZ, respectively. It was also noted that the obtained frequency corresponded to the microwave frequency and was different from the intensity maximum of the wavelength due to a mathematical difference when switching between wavelength and frequency dependence.
  • #1
Fabio010
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0

Homework Statement



The cosmic microwave background radiation has a blackbody type spectrum. Determine its max frequency and the correspondent wavelenght. Verify if found frequency is a microwave frequency and compare with the following curve:


Untitled(2).jpg




Homework Equations



Using the Wien Law displacemente, and knowing that CMBR has a thermal black body spectrum at a temperature of 2.725 K. We can easily calculate the wavelength peak and its frequency.

λmax = 1,06mm

frequency = λmax/c = 2,83E11HZ


We can verify that the frequency that we obtained corresponds to the microwave frequency.

But when i am comparing with this curve
Untitled(2).jpg
, i did not find any relation...

I just do not know what is the relation of the graphic with the obtained results.

Anybody to help? Help is always appreciated.!
 
Last edited:
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  • #2
That is a tricky problem.

The curve shows the frequency-dependence of the intensity (waves/cm is proportional to frequency) - you can calculate the wavelength which corresponds to its peak, and it will not agree with your wavelength.

This is not an error on your side, it is a surprising mathematical result: If you switch between wavelength and frequency dependence, you get different positions of the peaks, as "per wavelength" on the y-axis is different from "per frequency".
 
  • #3
mfb said:
That is a tricky problem.

The curve shows the frequency-dependence of the intensity (waves/cm is proportional to frequency) - you can calculate the wavelength which corresponds to its peak, and it will not agree with your wavelength.

This is not an error on your side, it is a surprising mathematical result: If you switch between wavelength and frequency dependence, you get different positions of the peaks, as "per wavelength" on the y-axis is different from "per frequency".

So, the difference is the switching from wavelength to frequency dependence. The results are "mathematically" equal?
 
  • #4
The intensity maximum of the wavelength is different from intensity maximum of the frequency - even if the curves correspond to the same spectrum.
 
  • #5
Understood!

Thanks a lot for the help!
 

Related to Cosmic microwave background radiation

1. What is cosmic microwave background radiation?

Cosmic microwave background radiation, also known as CMB radiation, is a type of electromagnetic radiation that fills the entire universe. It is the oldest light in the universe, dating back to about 380,000 years after the Big Bang.

2. How was cosmic microwave background radiation discovered?

CMB radiation was first predicted by scientists George Gamow, Ralph Alpher, and Robert Herman in the late 1940s. It was then accidentally discovered in 1964 by Arno Penzias and Robert Wilson, who were conducting experiments with a radio antenna and noticed a constant, low-level noise coming from all directions.

3. What does the cosmic microwave background radiation tell us about the universe?

The CMB radiation provides evidence for the Big Bang theory and gives us a glimpse into the early stages of the universe. It also helps us understand the composition and evolution of the universe, as well as confirm theories about dark matter and dark energy.

4. How is cosmic microwave background radiation measured?

CMB radiation is measured using specialized telescopes and satellites that can detect microwaves. Scientists analyze the intensity and polarization of the radiation to gather information about the age, shape, and temperature of the universe.

5. Can cosmic microwave background radiation be seen with the naked eye?

No, CMB radiation cannot be seen with the naked eye as it is a form of invisible light. However, it can be detected and measured using specialized equipment and technology.

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