Khan Academy
Khan Academy: Discovery of the Electron and Nucleus
Learn about Thomson's cathode ray experiment and the plum pudding model and Rutherford's gold foil experiment.
University of Colorado
University of Colorado: Physics 2000: Temperature and Absolute Zero
A thorough, multipage discussion of color and color television sets that explains how an image is formed on the television using red, green, and blue light. Understandable discussion, excellent graphics, and many interactive Java applets.