Blacklight facts for kids
A blacklight is a special type of light that gives off mostly ultraviolet (UV) light. This UV light is called "UV-A." Blacklights give off very little light that you can actually see.
Some blacklights have a special purple filter on the bulb or in the lamp. This filter blocks most of the visible light. It lets the UV light pass through. This is why these lamps have a dim purple glow when they are on. These lamps are often called "BL" lamps, which stands for "blacklight."
Other blacklights produce UV light but don't have this filter. They give off more visible light and look blue when they are on. These are often used in "bug zapper" insect traps. They are called "BLB" lamps, meaning "blacklight blue."
Blacklights can be made in different ways. They can be special fluorescent lamps, mercury-vapor lamps, LEDs, or even lasers. In medicine and forensics, a blacklight is sometimes called a Wood's lamp. This name comes from Robert Williams Wood, who invented the special glass filters used in early UV lights.
Many other lamps give off UV light along with visible light. But blacklights are important when you need UV-A light without much visible light. This is especially true for seeing fluorescence. Fluorescence is a cool colored glow that many things give off when UV light shines on them.
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What Are Blacklights Used For?
Blacklights have many interesting uses. They are used for fun lighting effects in art and at parties. Doctors use them for some tests. They can also help find things that have been marked with special fluorescent dyes.
Finding Hidden Things
Blacklights are great for finding things you can't see with regular light.
- Rock hunting: Some rocks and minerals glow brightly under a blacklight. This makes them easier to find.
- Checking money: Blacklights help spot counterfeit money. Many banknotes have special security features that glow under UV light.
- Finding leaks: Mechanics use blacklights to find leaks in refrigerators and air conditioning systems. They add a fluorescent dye to the system, and if there's a leak, the dye glows under the blacklight.
Art and Entertainment
Blacklights are popular for creating cool visual effects.
- Glowing art: Artists use special paints and decorations that glow under blacklight. This creates amazing, bright displays.
- Parties and clubs: Blacklights are often used in nightclubs and at parties to make clothes and decorations glow.
Science and Health
Blacklights also have important uses in science and health.
- Medical tests: Doctors use Wood's lamps to check for certain skin conditions or infections.
- Curing resins: Some plastic resins and glues harden very quickly when exposed to UV light from a blacklight. This is used in dentistry and other industries.
- Tanning beds: Strong UV-A lights are used in tanning beds to help people get a tan.
Are Blacklights Safe?
The low-power UV-A light from typical blacklights is generally safe for your skin and eyes. You can look at them without special protection. However, very powerful UV light sources, like those in tanning beds, can be dangerous. You should always use personal protective equipment like goggles and gloves when around strong UV lights.
Images for kids
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Compact fluorescent (CF) black light bulb
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Spectrum of a black light fluorescent tube. The tiny secondary peak is light from the mercury vapor line at 404 nm leaking through the filter, which gives the lamp its purple glow.
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100-watt incandescent black light bulb
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A 160-watt mercury vapor black light
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UV LED
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Fluorescein glowing under ultraviolet light
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Uranium glass glows under UV light.
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The security thread of a US $20 bill glows green under black light as a safeguard against counterfeiting.
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Anti-counterfeiting design of a Chinese passport glows under black light.
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Scorpion fluorescing under ultraviolet from a black light
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Decorative use of black light in a nightclub
See also
In Spanish: Luz negra para niños
