Welcome to the Blackbody Radiation page, part of the 'Utility Applets' library of TEST, The Expert System for Thermodynamics. TEST is a network of HTML pages with embedded Java Applets that helps users solve thermodynamic problems and perform parametric studies visually without any programming.

To determine spectral or total radiation from a blackbody within a range of wavelength (or band) simply enter the temperature, and the limits of the wavelengths, and click the 'Calculate' button.

The examples below contain images of the Blackbody Radiation table in action. Once you get a rough idea about how it works, you can start using the real thing by following these instructions.

There are two ways of doing anything, the quick way and the right way.

If you are in a hurry, do the following: (a) Browse the examples below (takes only a minute), and (b) Launch the customized Java applet (called a daemon) by clicking the appropriate link at the top of this page. If you have a modern browser (Netscape 4.5 or better, Microsoft IE 4.0 or better), the daemon will appear in about 10-50 seconds (1 second if you are running from a locally installed TEST) and you can start exploring.

To fully exploit TEST follow thest steps: (a) Start the Introduction/Turorial for the Expert System by clicking the link at the top of this page. (b) Explore a few daemons as explained in the tutorial. (c) Browse a few topics of your choice from the Slide Show. (d) Once you understand the algorithm TEST applies for locating the right daemon for a given problem, you can use the TEST-Map to quickly launch a desired daemon. Of course, all these may take better part of an hour - but, trust me, you will not regret it.

 

Example-1:The Sun has an effective blackbody temperature of 5555 K. What fraction of radiation is contained in the visible domain (0.4-0.7 mic)?  Solution:To bring up the appropriate daemon click the 'Blackbody Radiation Applet' link at the top.  As the daemon gets loaded, you may see its shadow for about 5-15 seconds.    Fig. 1. Image of the Blackbody Radiation Daemon producing solution to Example 1. Enter the temperature and the wavelength range. Click the 'Calculate' button to produce F (the fraction of radiation within the given range).

 

Example-2:A tungsten lamp has a filament temperature of 4000 K. What fraction of the radiation is in the infra-red region? Solution: Enter the temperature and the wavelength range .7 to say 20 micron. Click 'Calculate' to produce F. Fig. 2. Image of the Blackbody Radiation Daemon producing solution to Example 2.

These examples are only meant to give the reader the flavor of a daemon (applet). Many more examples of solved problems, grouped into fifteen different chapters, can be found under TEST Home Page> TEST> Problems page. Before you start using this particular applet, it is strongly recommended that you take a look at the 'Slide Show' to get a feel for the breadth of thermodynamic topics TEST covers. Besides more examples and a visual tour, you will also find a visual manual for the daemons explaining different buttons and widgets found in the daemons. You will see how a wide range of thermodynamic problems can be visually solved and parametrically studied without the need for a single line of programming.