PROCEDURE
Click this link of the Blackbody Spectrum simulator. If you are using a printed version of this
document, then type this link on your internet browser.
https://phet.colorado.edu/sims/html/blackbody-spectrum/latest/blackbody-spectrum_en.html
Ensure the “Graph Values” is checked. See the image on the right.
You can control the blackbody temperature, and notice that for every given
temperature the peak of the spectrum corresponds to a particular wavelength.
For example, if the temperature is T = 5350 K the peak corresponds to the
lambda Ȝpeak = 0.542 ȝm. See the snapshot below:
Fill in the following table of Ȝpeak values for every temperature T and calculate 1/T. For this part,
you may use any spreadsheet programs. We suggest using the Google Spreadsheet.
T (K) 1/T (K-1) Ȝpeak ȝm)
500
1000
1500
2000
3000
4000
6000
10,000
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- Plot Ȝpeak vs 1/T using the scatter plot as you did in the previous experiment. Make a
linear fit of the data (add a linear trendline) by selecting the intercept at zero. Display an
equation of this fit on the chart. What value of “b” do you get? (Attach your plot to this
lab report).
b =BBBBBBBBBBBBBBBBBBBBBBBBBBBȝPڄK - Calculate the discrepancy error, |b – 2898| / 2898 × 100% and comment about your
finding. Does it agree with the theoretical value? - Using your value of b and the Wien’s Displacement equation, predict the surface
temperature of a neutron star whose peak wavelength is observed in the x-ray region of
Ȝpeak ȝm.
T = _______________ K - The normal human body temperature is T = 310 K. At what wavelength would humans
emit the blackbody radiation? What region of the electromagnetic spectrum does it
correspond to?
Ȝpeak,human = _______________ ȝm. - Can you now explain why blue stars hotter than the red stars?
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Sample Solution
