Black Lights - How They Glow

One of the many things in life that seems to fadeis known as a phosphor.
away when a person enter adulthood alongside cottonMany things are a phosphor. Natural phosphors include
candy and candy necklaces would have to be blackteeth and fingernails and some manmade materials
lights. This kind of lighting is usually only significant for awith phosphors include some fabrics (think of the
few school dances in junior high, but how they work isglowing white t-shirt), highlighters and television screens.
pretty interesting for anyone who thinks learning is aBlack lights are available in two bulb types - one like
lifetime pursuit.the traditional incandescent bulb and another like a CFL.
Most of us have been introduced to the light spectrumThe tubular shaped bulb is like a CFL light becauseit is
at some point, but we will refresh in case 7th gradefilled with an inert gas and a bit of mercury, but the
science was some time ago.phosphor coating is different from a traditional CFL in
The spectrum goes as follow:that the one used in a black light soaks up dangerous
Radio - Microwave - Infrared - Visible - Ultraviolet -waves and only emits ultraviolet light to shine (and a
X-Ray - Gamma Raylittle bit of violet sometimes).
These waves go from long wave length to short andThe black light that is basically just an incandescent
as humans we can only see the waves in the middleincludes a light filter which absorbs everything the
of the spectrum, appropriately labeled "visible". Withinfilament emits except the ultraviolet light.
the "visible" section we can see light in the differentSo there you have it: two pretty typical bulbs, CFLs
colors: red, orange, yellow, green, blue, violet. Afterand incandescents, jimmy-rigged a bit to release only
violet we hit ultraviolet light which our eyes cannot see.ultraviolet light and we have black light ready to make
Why the lengthy, and probably a bit dull explanationphosphors out there glow!
you are asking? Simply so that we can all completelyOf course, black lights aren't only used at dance clubs;
understand the next statement-there are many practical uses as well. Mechanics use
Black lights produce ultraviolet light, which we cannotthem to find tiny leaks by injecting fluorescent dye into
see. However, we can see a glowing purplethe liquid that might be leaking, police use them to
sometimes, which makes perfect sense because it ischeck if money is counterfeit since US money has an
just a step below on the light spectrum.invisible fluorescent strip in each bill and forensic
But the waves that we cannot see coming out of thescientists use the lights at crime scenes to find
black light really isn't what makes them special; it is thefingerprints and other evidence.
way they make everything in the vicinity seem to glow.Whether used to solve a crime or just to make the
What we see glowing is actually any substance thatdance floor glow - black lights can be a fun thing to
emits light when it is hit with some sort of radiation, thishave around.