How does a fluorescent light bulb work?

Answer 1

"Friction" is used loosely here: this can more accurately be called electric resistance. "Friction" in the bulb filaments opposes current at a very minimal amount. This gives off heat, explaining why a bulb is hot. Also this "friction" prevents strong current from burning things out. All of our daily electrical appliances have tons of resistors in them.

Answer 2

An incandescent light bulb takes just enough electric current to make a piece of metal glow brightly enough to give out visible light yet not get so hot that it melts and breaks. The piece of metal is called a tungsten filament.

Experiments were made with different materials to use as the filament, including natural fibres, pure metals and alloys of different metals, to find the material which had the longest life whilst glowing brightly enough to give out visible light. The metal Tungsten was found to be the best.

Also experiments were made trying a vacuum or different kinds of gas inside the glass bulb to find out which was the best. For many years Nitrogen gas was found to be the best but other gases or mixtures of gases may now be used. Fluorescent light bulbs electrically charge a gas (sometimes one of the inert gases like argon).

Whilst it is normal everyday talk to say that a light bulb or a lamp is "burning", that is not strictly accurate because, speaking strictly scientifically, the word "burning" has a very precise meaning. When something is said to be "burning" it means the material is combining with the element Oxygen to form a compound called an Oxide.

For example when Carbon is burnt it makes either Carbon Monoxide or Carbon Dioxide or a mixture of those two gases. How much of each is made depends on the actual conditions in which the Carbon is being burnt. That is why it is scientifically correct to say that a light bulb is "glowing" and not that it is "burning".

Modern light bulbs don't hold a vacuum. Instead they are filled with an inert (electrically nonconducting) gas such as Nitrogen. An inert gas is used to fill the bulb (instead of just pumping out almost all the air to leave a near vacuum) because the action of filling the bulb with an inert gas can be used to flush away ALL of the air. In addition the inert gas has the very useful physical property of helping to conduct heat from the glowing filament to the glass bulb. This allows the whole surface area of the glass bulb to radiate heat into the surrounding air.

It is important to understand that the inert gas does not allow the filament to "burn away", it just allows it to glow brightly. If some air were still present in the bulb - as sometimes happens if a light bulb gets knocked and gets even a tiny crack in its glass bulb - then the oxygen present in ordinary air will quickly make the filament burn away.

If the light bulb just held a vacuum (as was the case in the early days of electric lighting) the main way the heat from the hot glowing filament could get out was along the wires feeding current to the filament and also along the insulators which support the filament. (Relatively little heat passes through a vacuum compared with what can pass through an inert gas.) So the feed wires and insulators got very much hotter compared to the temperature they reach in modern light bulbs. This caused the old vacuum light bulbs, which glowed at a much higher temperature than radio tubes, to have a much shorter useful life compared to vacuum radio tubes.

An earlier answer was given saying the filament has to be made from a material that has a negative temperature coefficient (as temperature increases, resistance decreases) but, if that were correct, then the decreasing resistance would cause more and more current to be taken as the lamp heated up - and the temperature would get higher and higher in a runaway manner - until either the power supply's breaker would trip or (more likely) the light bulb's filament would simply explode!

In fact the filament has to be made from a material that has a positive temperature coefficient. (As temperature increases, resistance increases.) Then, as the bulb's temperature rises, its filament's increasing resistance causes less current to be taken than when it was cold. Quite quickly a stable "steady-state" temperature and "running" resistance is reached so that the bulb simply continues to give out a steady amount of light according to the current it is taking from the electricity supply.

A thread of metal, usually tungsten, is used as an electrical filament to convert electricity into light in incandescent light bulbs (as developed in 1878 by Joseph Wilson Swan, among others), and into heat in vacuum tube devices.

The first successful light bulb filaments were made of carbon (made from oxidized bamboo), later replaced with tungsten.

An electrical current travels through the filament and because of the electrical resistance of the filament makes it white-hot and generates light and heat. It is normally in a vacuum or a noble gas or inert gas inside a glass enclosure to stop oxidation. Small amounts of a halogen can be added to facilitate transport of evaporated tungsten atoms back to the filament, resulting in significantly prolonged lifetime when used at higher temperatures, which is exploited in halogen lamps. Electrical filaments are used in hot cathodes of various types of vacuum tubes and electron guns as sources of electrons.

You get light illumination from an incandescent lamp because current flowing through the filament, which has nonzero resistance, causes a voltage drop across the filament. That combination of voltage and current represents power. Power heats the filament to the point of incandescence, creating light. The bulb is evacuated of air, or filled with an inert gas, so that the filament does not burn up from the combination of heat and oxygen.

Other lights, such as fluorescent tubes and bulbs, contain argon gas and Mercury vapor instead of a filament. When the electricity flows through the gas UV (ultraviolet) radiation is emitted. The UV radiation hits phosphors coated on the inside of the bulb, which then emit visible light.

A very technical explanation

A standard incandescent lamp will light up because when we energize it by turning it on, electric current flows through the filament in the lamp and heats it so hot that it reaches incandescence. That means that the atoms of the filament are being ionized by the heat. The outermost electrons, the valence electrons in the atoms of the filament, are absorbing energy and jumping out to higher energy levels, and then falling back with the emission of a photon - light. All those atoms are being ionized and all those electrons are jumping to higher energy levels and then falling back by emitting a photon. That's what incandescence is. And the lamp filament is being heated to white hot, to incandescence, by the electricity. That's why they light up.

Incandescent light bulbs work by heating a thin strand of tungsten to high temperatures, causing it to glow brightly. Tungsten has the highest melting point of any element and therefore is perfectly suited for this purpose.

In a lightbulb at the very tip is a thin wire made of a material called tungsten when electricity passes through it, it heats up and glows white hot, however if it is in contact with oxygen it will blow, therefore the glass is around it to keep nitrogen inside the bulb and keep oxygen out.
When electricity passes through a filament (the curly bit of wire in a light bulb) it takes more effort to go through because it's so thin, so it glows.

Answer 3

Fluorescent light bulbs have a gas inside of them called mercury. The way that the light bulb works is that it uses electricity to "excite" the mercury atoms. This causes the mercury atoms to give of short wave ultraviolet light. this causes a phosphor which is any substance that can illuminate to fluoresce or emit light.

Answer 4

A fluorescent light bulb works in the following concepts; it has a glass tube filled with mercury vapor which is also coated with mercury substance. at the end of each tube are two coiled tungsten which gets hot and glow producing the light inside the fluorescent.

Answer 5

=A light bulb glows because electricity goes through it.=