NASA
Nasa: Oersted and Ampere Link Electricity
NASA provides a nice blending of the achievements of three scientists, Oersted, Ampere, and Maxwell. This done by NASA-sponsored International Solar-Terrestrial Physics group. Lots of pictures, diagrams, and scientific explanation. Good...
NASA
Viewing the Violent Universe: What Are Gamma Rays?
The universe produces a broad range of light, only a fraction of which is visible to our eyes. Gamma rays are nonvisible light, which also includes x-rays, ultraviolet light, infrared radiation, and radio waves.