The term "light" can be used to describe incandescent light, fluorescent light, black light or sunlight. These different kinds of light are made up of different heat energy -- some that are invisible to the naked eye, such as ultraviolet light. Ultraviolet A, or UVA, is what causes skin aging and wrinkling and ultraviolet B, or UVB, is what causes skin reddening and sunburn.
UV beads are embedded with a chemical substance containing pigment. The pigments change color when they absorb electromagnetic radiation between 360 and 300 nanometers in wavelength. The UV beads remain white when they're not exposed to UV rays, such as when they are indoors and away from sunlight. However, the UV-sensitive beads change color when they are outdoors and exposed to sunlight. Lights that have no UV radiation, such as light emitted from lightbulbs, don't change the color of UV beads.
The presence of UV light can be tested using UV beads in several ways. One way is to use the UV beads to test the effectiveness of your sunglasses. Go outside when it's sunny and hold the beads in one hand and place your sunglasses over the beads. If the beads stay white that means that your sunglasses are doing their job by blocking UV rays. The effectiveness of sunscreen can also be tested using UV beads by coating the beads with sunscreen. Place the beads under sunlight and observe if they change color. Likewise, you can test the effectiveness of dark medicine glass or plastic bottles that block ultraviolet light by placing a few beads inside and testing to see if they change color when the bottle is exposed to sunlight.
Experiments using UV beads can help teach students about the power of sunlight, ultraviolet radiation and the damages that UV rays can cause when they are exposed to it. Students can be taught protective measures that they can take to avoid harmful UV rays both indoors and out. Students can also recognize that sunlight emits rays that man-made light does not; and that sunlight emits both rays that we can and cannot see.