What can spectra tell us about temperature?

Stars are too far away (and too hot!) for a human to touch, yet we can measure their temperatures. Spectra make this possible! Let’s investigate how.

Incandescent Bulb Temperature

An incandescent light bulb is a type of bulb that generates light by running electricity through a very thin metal filament, causing it to heat up and emit thermal radiation.

Spectrum Tool.

  1. source 1 shows the spectrum of an incandescent light bulb.
  2. Under source 2, use the Select thermal model dropdown menu to find the temperature with a spectrum that provides the best match to the bulb's spectrum.

Note: The y-values of these model spectra are not plotted on the same scale—they have been modified so they can all be plotted in the range of the tool. The key is to compare the overall shape of the curves, and most importantly, where the peaks are.

Spectrum Notebook. Answer the questions in your Notebook.

  1. What temperature thermal spectrum best matches the spectrum for the incandescent light bulb?
  2. How does the temperature of the light bulb compare with the temperature on the surfaces of the stars you investigated in the previous section?
Source 1:
Lamps — Incandescent Bulb
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (microns)
Source 2:
 
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (microns)
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