a. Wien's law gives the wavelength where the blackbody peaks as a function of temperature.

By playing with the Applet can you tell how high the temperature has to be for the peak of the curve to fall outside the visible spectrum? Can you use Wien's law to determine at what exact wavelength the peak occurs?

b. If the peak of the curve falls outside the visible range, what determines the color of a star? White light has an approximately equal mix of colors. White dwarfs are high temperature stars (T > 30,000 K). Can you use the Applet figure out how they got their name?

c. The luminosity relation for blackbodies says that if two stars have the same radius but different temperatures, the hotter (bluer) star is a whole lot brighter than the cooler (redder) star. Just in case you forgot here is the luminosity relation,

You can also see this by using the applet to plot two blackbody curves of different temperature. The applet uses the first plot you created to set the scale of y-axis (which is the radiation's intensity). When you plot the second curve you can then see how its intensity compares to the first. Try plotting a high temperature blackbody curve and then, using the "new graph" button, try plotting one with a slightly lower temperature. Does the second curve peak below the first one? What does that tell you? Now try plotting a third curve that has a slightly higher temperature. Does the peak of this curve rise so far that it is off the plot? What is this telling you?

Physically, why do you think the intensity in a blackbody is so dependent on temperature?