luxemozione

In a previous article we talked about overcoming incandescent bulbs and their future withdrawal from mareco and gradual replacement with more energy efficient.
In this' article I will summarize in a (hopefully) more clearly as possible the principle of operation.
Let's leave out the troubled history of the invention of the incandescent lamp, Edison attributed to the American and talk about how and what is covered by a light bulb.
All more or less have done this as an incandescent lamp, a spherical glass body and a base metal screw.
But what's all'inteno the globe of glass? first find a filament of a metal, the Tungseno, characterized by low electrical resistance, this is supported by means of metal rods and a glass support, within an environment where there is an inert gas to low-pressure argon or krypton, note how the tungsten filament is not linear but "double spiraling" (see photo).
dove E=energia irradiata, T=temperatura espressa in Kelvin e σ= costante di Stefan-Boltzmann ( The operation of the lamp with tungsten filament is due to a number of traditional laws of physics: first among them the law of "Stefan-Boltzman," according to which the energy radiated per second from a black body is proportional to the temperature in Kelvin, raised to the fourth power, or E = σ T ⁴ where E = energy radiated, T = temperature in Kelvin, and σ = Stefan-Boltzmann constant ( ).
From this it follows that if we subject a black body at a certain temperature this energy and emit much higher the temperature at which it is submitted so the lower the wavelength at which radiation émettre (Law Wien).

Now, the tungsten is not a black body itself, but can be assimilated to it.
Thus the passage of current through the tungsten filament is heated to a temperature of about 2700K (the melting point of tungsten is 3422 ° C), with consegente emission of energy, part of which, very little indeed, in the spectrum the visible.
viene emesso sopra i 780 nm, cioè nell'infrarosso (IR) , e quindi disperso come calore. Consequently, the reason for poor light efficiency of the conventional lamp, with only 5-7% of the energy emitted by the tungsten falls within the visible spectrum (between 380 and 780 nm), approximately 93-95% is emitted over and 780 nm, ie infrared (IR), and then dispersed as heat.

Note that for light efficiency means the ratio of the luminous flux (lm) emitted and the electric power consumption (W) and is expressed in [lm / W].
Normally a 100W incandescent lamp has an absorbing issue of flow of about 1000lm, the result is an efficiency Light 10LM / W

Post that may be of interest

1. Long life incandescent light bulbs
2. Via incandescent lamps!
3. Readmitted incandescent bulbs. No!
4. September 2009, as a bulb dies
5. World Environment Day CFL vs. Incandescent
6. incandescent lamps goodbye??