Why Do Somethings Glow In the Dark?
A phosphor is a chemical substance that when energized radiates (emits, gives off) visible light.
NOTE: Phosphors may or may not contain the phosphorus element.
Scientists have created thousands of different kinds of phosphors. Phosphors differ in:
1. The type of energy that is needed to energize them.
2. The color of the visible light that they give off.
3. The length of time that they glow after being energized, which is known as the persistence time.
Some phosphors emit visible light as long as they are being energized. But emit no light once the energizing source is removed. Other types of phosphors continue to emit visible light after the source of energizing energy is removed. These phosphors are said to be phosphorescent, such things that glow-in-the-dark.
Glow-in-the-dark toys contain phosphors that are phosphorescent. These phosphors can be energized with visible light, such as from sunlight or a light bulb.
Zinc Sulfide and Strontium Aluminate are commonly used for glow-in-the-dark materials. Of these two phosphors, strontium aluminate has a longer persistence time.
Some phosphors must be energized by ultraviolet radiation (commonly called UV light). A source of UV light is sunlight and a black light.
For Information about purchasing a black light as well as Glo-Germ Lotion to demonstrate how germs spread as well as proper hand washing techniques, See Black Light Supplies
For information about how a black light works, see How Stuff Works: Black Light
There are natural phosphors, such as in the phosphors in the exoskeleton of scorpions. A scorpion will glow if you shine a black light on it, but stops glowing when the light is removed. Thus, the phosphors in a scorpion’s exoskeleton are energized by the UV light from the black light, and the phosphors are not phosphorescent.
Vaseline (petroleum jelly) contains chemicals that exhibit phosphorescence when excited with black light.
Glowing Phosphors
Discover This For Yourself
Use Vaseline (petroleum jelly) to draw a picture on your hand, such as the smiley face shown in the photo. Then, in a darkened room, shine a black light on your hand.
CAUTION: DO NOT SHINE BLACK LIGHT INTO YOUR EYES. IT COULD PERMANENTLY DAMAGE YOUR EYES.
 |
Help! My Science Project is Due Tomorrow! Easy Experiments You Can Do Overnight |
Connect With Me