electromagnetic radiation

Unlike the water waves in a ripple tank, that are oscillating water molecules, or sound waves, that are oscillating air molecules in light waves there are no actual physical particals that move. Instead light is made from electric feilds and magnetic fields oscillate together (but perpendicular to each other.)

Light, electricity, and magnetism are manifestations of the same thing called electromagnetic radiation. The energy you see coming out of the computer screen you are using to read this page is made of fluctuating electric and magnetic energy fields. This energy comes in many forms, some have wavelengths that are detectable by our eyes but others can not be seen such as infrared (IR), radio, X-rays, ultraviolet (UV), and gamma rays.

All these electromagnetic waves carry energy and we can use it in many different ways for example ultraviolet light has high enough energy to damage our skin cells (we tan as a defense mechanism). Special UV bulbs called ``black lights'' are used by hospitals to kill bacteria. Because X-rays have such high energy they can pass through skin and muscle but are stopped by bone.

The link below to go to a diagram of different wavelengths of electromagnetic radiation and some of the properties of the different parts of this spectrum.

http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edit.svg