Ejs Open source java applet Blackbody radiation curves customised for nm written by Fu-Kwun Hwang and customized by Loo Kang WEE
Ejs Open source Blackbody radiation curves customised for nanometre nm  
This applet will show 5(with temperature text) to 10(in total) black curves of black body radiation curve between Tmin and Tmax.
Minimum temperature shown can be adjusted with left slider bar, Tmin=
Another curve in red is also shown (it's temperature can be adjusted with middle slider bar), T= Maximum temperature shown can be adjusted with right slider bar, Tmax= You can use it for study the intensity for black body radiation. If you want to study different temperature range, You can change Tmin and Tmax, to change the temperature range,too, currently it is set to 100 K to 10000 K. The x-axis shows the wavelength ? is in nanometre for prefix 10-9 SI units
the intensity is in W.e-5 / (m2.nm)
The wavelength unit in the simulation is nm (nanometre), remixed from
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=427.msg3833#new for original (angstrom) version by Fu-Kwun Hwang.
Please note that this resource requires at least version 1.5 of Java (JRE).

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=427.msg3833#new for original (angstrom) version

/htdocs/ntnujava/ejsuser/14019/users/sgeducation/lookang/BlackbodyRadiationSpectrum_pkg/BlackbodyRadiationSpectrum.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop. This work is licensed under a Creative Commons Attribution 2.5 Taiwan License
Download EJS jar file(1006.2kB):double click downloaded file to run it. (53 times by 25 users) , Download EJS source (16 times by 10 users) View EJS source

What is a blackbody radiation?
reference: http://en.wikipedia.org/wiki/Black_body
A black body is an idealized physical body that absorbs all electromagnetic radiation falling on it. Because of its perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum that depends on the body's temperature. At Earth-ambient, low temperatures this emission is in the infrared region of the electromagnetic spectrum and not visible, and therefore the object appears black, since it does not reflect or emit any visible light.
t is called blackbody radiation and has a distribution with a frequency maximum that shifts to higher energies with increasing temperature. As the temperature increases past a few hundred degrees Celsius, black bodies start to emit visible wavelengths, appearing red, orange, yellow, white, and blue with increasing temperature. By the time an object is visually white, it is emitting a substantial fraction as ultraviolet light.
As the temperature decreases, the peak of the blackbody radiation curve moves to lower intensities and longer wavelengths. The blackbody radiation graph is also compared with the classical model of Rayleigh and Jeans.

How is it constructed?
The concept of the black body is an idealization, as perfect black bodies do not exist in nature. Graphite is a good approximation, however. Experimentally, blackbody radiation may be established best as the steady state equilibrium radiation in a rigid-walled cavity. A closed box of graphite walls at a constant temperature with a small hole on one side produces a good approximation to ideal blackbody radiation emanating from the opening.