Why do fluorescent light bulbs need a ballast?
Fluorescent light bulbs need a ballast because they use a gas to create light. Regular light bulbs (also known as incandescent bulbs) create light by heating a filament inside the bulb. The heat makes the filament white-hot, producing the light that you see. In a fluorescent bulb, when the gas is excited by electricity, it emits invisible ultraviolet light that hits the white coating inside the fluorescent bulb. The coating changes the ultraviolet light into light you can see. (A lot of the energy used to create the heat that lights an incandescent bulb is wasted. Because fluorescent bulbs don't use heat to create light, they are far more energy-efficient than regular incandescent bulbs.)
The combination of gas, electricity, and coating in a fluorescent bulb is so effective at producing light that, without something to regulate the electricity flowing into the bulb, the light will continue to gain intensity until the bulb stops working. That's where a ballast comes in — it supplies the initial electricity that creates the light, and then it regulates the amount of electricity flowing through the bulb so that the right amount of light is emitted.
What is a ballast, and how does one work?
A ballast is an electrical component used with a fluorescent bulb (or mercury vapor lamp or arc lamp) to conduct electricity at each end of the tube. It supplies the initial electricity to the bulb that creates light, and then it regulates the amount of electricity flowing through the bulb so that it emits the right amount of light.
What makes compact fluorescent and fluorescent bulbs more energy-efficient than regular bulbs?
Fluorescent light bulbs (including compact fluorescents) are more energy-efficient than regular bulbs because of the different method they use to produce light. Regular bulbs (also known as incandescent bulbs) create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see. A lot of the energy used to create the heat that lights an incandescent bulb is wasted. A fluorescent bulb, on the other hand, contains a gas that, when excited by electricity, hits a coating inside the fluorescent bulb and emits light. Because fluorescent bulbs don't use heat to create light, they are far more energy-efficient than regular incandescent bulbs.
Do light bulbs (such as compact fluorescent bulbs) give off hazardous amounts of ultraviolet (UV) light?
Regular fluorescent light bulbs used in your home and office do not produce a hazardous amount of ultraviolet light (UV). Most light sources, including fluorescent bulbs, emit a small amount of UV, but the UV produced by fluorescent light bulbs is far less than the amount produced by natural daylight. (Ultraviolet light rays are the light wavelengths that can cause sunburn and skin damage.)
Your safety is important to us; that's why, for all of our light bulbs designed for general public use, we strive to minimize the amount of UV light emitted.
If you're looking for a low-UV bulb for an especially sensitive area, try our Saf-T-Gard® bulbs. They block most ultraviolet light emissions, and they're also shatter-resistant.
Where can I find lighting disposal policies and contact information for my state or province?
Please refer to our state disposal policies page. In most states, fluorescent and compact fluorescent light bulbs used at home can be disposed of in the same way as regular light bulbs. While all fluorescent bulbs contain a trace amount of mercury, the quantity is so minute that disposal is not regulated by federal standards (established by the EPA, the Environmental Protection Agency). You would have to dispose of an incredibly large amount of fluorescent bulbs — around 360 4-foot fluorescent tubes — before you would be subject to federal disposal standards. However, individual states and provinces also have established disposal standards, so you should check the disposal policies in your area.
How much heat (or infrared radiation) is emitted by regular, halogen, and compact fluorescent light bulbs?
Regular light bulbs, known as incandescent bulbs, create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see. Halogen light bulbs create light through the same method. Because incandescent and halogen bulbs create light through heat, about 90% of the energy they emit is in the form of heat (also called infrared radiation). To reduce the heat emitted by regular incandescent and halogen light bulbs, use a lower watt bulb (like 60 watts instead of 100).
Fluorescent light bulbs use an entirely different method to create light. Both compact fluorescent bulbs and fluorescent tubes contain a gas that, when excited by electricity, hits a coating inside the fluorescent bulb and emits light. (This makes them far more energy-efficient than regular incandescent bulbs.) The fluorescent bulbs used in your home emit only around 30% of their energy in heat, making them far cooler than regular bulbs and an ideal choice whenever reducing heat from bulbs is important.
What's the white powder I see inside my fluorescent bulb?
The white powder that you see inside a fluorescent lamp is called phosphor, which is a substance that emits white, visible light whenever it absorbs light waves. Both compact fluorescent bulbs and fluorescent tubes contain a gas that gives off invisible light when excited by electricity. This invisible light travels to the phosphor coating on the bulb, where it is transformed into light visible to the human eye.
What's the difference between a blacklight and a blacklight-blue bulb?
Blacklights are fluorescent lights that are designed to emit a specific type (UVA) of ultraviolet light (although a small amount of visible light is emitted as well). Blacklights are good for making certain substances that would normally be invisible glow (or "fluoresce"). For example, you may have had your hand stamped at an amusement park with an invisible ink that, when viewed under a blacklight, glowed a bright neon color. Blacklights are available in Fluorescent and Incandescent. Fluorescent Blacklights are great to use for a party or blacklight poster; Incandescent Blacklights are an inexpensive way to create a party atmosphere.
Blacklight-blue bulbs are designed with a special deep-blue glass that filters out visible light, producing the maximum amount of ultraviolet light possible. If you're looking for a blacklight that produces the minimum amount of visible light for an especially sensitive area, blacklight-blue bulbs are an ideal choice.