Incandescent lamps are the most widespread electrical light sources that are primarily used to illuminate rooms and workplaces, as well as for vehicle lighting.
In the case of incandescent lamps, the lighting effect of the electric current is used when the current flows through a metallic conductor, the filament.
The first incandescent lamps were developed by the German HEINRICH GOEBEL (1818-1893), the Russian ALEXANDER LODYGIN (1847-1923) and the American inventor THOMAS ALVA EDISON (1847-1931). EDISON in particular succeeded in building the first incandescent lamps that were really useful in everyday life.
Incandescent lamps are the most widespread electrical light sources that are primarily used to illuminate rooms and workplaces, as well as for vehicle lighting. You will eg B. also used for flashlights and traffic lights.
In the case of incandescent lamps, the lighting effect of the electric current is used when the current flows through metallic conductors.
Structure and mode of operation
The most important parts of an incandescent lamp are a filament ( filament ) with a power supply, the base for connection to the power supply via a socket and the glass bulb.
This glass bulb is not only used to protect the glow wire. Inside the light bulbs, there is a gas mixture of argon and nitrogen, which is supposed to prevent the filament from evaporating quickly. The only filament used is tungsten, which has a high melting point of 3,380 ° C and only evaporates slowly even at high temperatures.
If electrical current flows through an incandescent lamp, the filament heats up very quickly to a temperature of around 2,600 ° C. This glowing metal wire emits a bright light. This means that electrical energy is converted into light and heat, and this heat effect is an undesirable but unavoidable phenomenon in normal incandescent lamps.
The first incandescent lamps were developed by the German HEINRICH GOEBEL (1818-1893) around 1854, the Russian ALEXANDER LODYGIN (1847-1923) and the American inventor THOMAS ALVA EDISON (1847-1931). Initially, carbon threads made from wood and plant fibres were used, but they were not very durable.
EDISON played a major role in the technical improvement of the incandescent lamp, which introduced the screw base that is still used today and improved the carbon filament lamp so that the first really usable incandescent lamps appeared around 1880.
Decisive advances were made when it was possible to process tungsten wire into incandescent filaments in 1914. A short time later, the gas filling was also introduced. Further progress has been made with the introduction of double helices.
However, all these incandescent lamps had one major flaw: the tungsten in the filament gradually evaporates and turns the glass bulb dark. From 1960 halogen light bulbs (also halogen lamps. The piston wall thus remains clear. The luminous efficacy of halogen lamps is higher than that of conventional incandescent lamps.
Efficiency and service life
Modern incandescent lamps also have a decisive disadvantage: their efficiency is very low at around 5%. So only 5% of the supplied electrical energy is converted into light and the remaining 95% into mostly undesirable heat. Significant advances have been made here with fluorescent lamps (energy-saving lamps), which are about five times as efficient. The average service life of incandescent lamps is around 1,000 operating hours. Then so much tungsten from the filament has evaporated that the filament burns through.
Types of light bulbs
Depending on the intended use, incandescent lamps come in very different designs, with different operating voltages and outputs.
In the household, incandescent lamps with an operating voltage of 230 V and an output of 25 W, 40 W, 60 W, 75 W and 100 W are used to illuminate rooms.
In vehicles with a 12 V electrical system, bulbs with
55 W – 60 W (main headlights), 21 W (brake lights, tail lights) and 5 W (indicators) are used.
For video lights and slide projectors, halogen lamps with operating voltages between 12 V and 230 V and outputs from 50 W to 200 W are usually used.
For flashlights, incandescent lamps with operating voltages between 1.5 V and 6 V are required. The power ranges from 1 W to 5 W.
They are a special design Infrared lamps that do not primarily use the light effect, but the heat effect of the electric current. A lower lighting effect can be achieved by lowering the temperature of the filament.