Color Temperature of a Blackbody Source
WingZ version [Mathematical Basis] [OpenOffice and Excel Versions]
Evaluation of the Planck blackbody equation. Demonstrates how the emission spectrum of a blackbody radiator depends on its temperature and emissivity.
This model can be used to determine whether a light source has a blackbody-like emission spectrum and to estimate its temperature and emissivity if so. Students take experimental measurements of the radiance of a light source at various wavelengths, type in the values of wavelength and radiance into the table on the right, then adjust the parameters of the model (temperature and emissivity) so that the calculated blackbody spectrum (shown by the red line) is a best fit to the experimental data points (shown by the blue dots).
Download links:
WingZ version:
black.wkz;
Wingz player application and basic set of simulation modules, for
windows PCs or Macintosh
OpenOffice and Excel Version
Other simulations that employ a blackbody source:
Signal-to-Noise Ratio of Absorption Spectrophotometry
Fluorescence Spectroscopy Signal-to-Noise Ratio
U.V.-Visible Spectrophotometer
Dual Wavelength Spectrophotometer
Blackbody temperature, T (in degrees K), set by on-screen slider.
Emissivity, set by on-screen slider.
Calculated radiance = emissivity*1.19111E+16*wavelength^(-5)/(exp(14380000/(wavelength*T))-1)
The graph shows a plot of calculated radiance (red line) and measured radiance (blue dots)
vs wavelength
Computes the spectral radiance, total radiance, and peak wavelength of a blackbody source, given the temperature and emissivity. Also plots spectral radiance vs wavelength from 150 nm to 3500 nm.
View Equations (.pdf)
Download spreadsheet in OpenOffice format (.ods)
Download spreadsheet in Excel format (.xls)
Note: to run the OpenOffice (.ods) spreadsheets, you have to first download the OpenOffice installer (download from OpenOffice), then install it (by double-clicking on the installer file that you just downloaded), and then download my spreadsheets from this page. Once OpenOffice is installed, you can run my spreadsheets just by double-clicking on them. Note 1: Don't use version 3.1. There is a bug in OpenOffice 3.1 that causes bad x-axis scaling on some of my graphs. The problems does not occur in version 3.0 or in the most recent version 3.2. Note 2: Downloading these files with Interent Explorer will change the file types from ".ods" to ".zip"; you will have to edit the file names and change the extensions back to ".ods" for them to work properly. This problem does not occur in Firefox or in Chrome.