Greg Pastrick, age 10, of Huntsville, Ala., for his question:

WHAT IS POLARIZED LIGHT?

Polarized light is made of light waves that have a simple, orderly arrangement. Ordinary light waves are arranged in a complex, disorderly manner. Light from the sun or from a lamp is ordinary light, and the waves vibrate in all directions perpendicular to the light beam. But polarized light waves vibrate in only one direction.

Light is polarized by having it pass through a filter or a number of filters. The filters absorb some of the light and transmit the rest.

There are many practical uses of polarized light in addition to sunglasses and photography. Polarized car headlights and windshields prevent glare from the lights of approaching cars. Microscopes can also be equipped with polarizers to give undistorted color.