Gas-discharge light sources are devices in which electrical energy is converted into optical radiation passing current through a gas (e.g., mercury in the vapor state; the mercury proved to be the best substance; as the pressure in a glass tube is low, the threat to the health of consumers is not). In short, under the influence of an electric field in mercury vapor is formed invisible to the human eye ultraviolet radiation.
Now, to make it visible, on the inner surface of the tube is applied a special substance is a phosphor. Changing the kinds of the phosphor, it is possible to vary the color characteristics of lamps.
Fluorescent lamps come in various shapes: straight tubular (linear), curly and compact (CFL). The diameter of the tubes may be in the range of 16-60 mm, but it is not related to the lamp power, which sometimes reaches 200 watts.
Linear light sources usually have a two-pin bases of the following types: g-13 (the distance between pins 13 mm) for lamps with a diameter of 40 and 26 mm, and G-5 for lamps with a diameter of 16 mm.
Fluorescent lamps are incredibly energy efficient. Their luminous efficiency depends on the capacity of start-up instrumentation and reaches values of from 50 to 90 lumens/watt is five times more efficient than incandescent bulbs! (Although, in fairness, we note that fluorescent lamps of low power and high fidelity is less effective).
Straight tubular fluorescent lamps work well in any position, however, the preferred horizontal orientation.
Fluorescent lamps are not designed to work when the air temperature is below 5°C: first, to "burn" the mercury discharge in sub-zero temperatures is much more difficult, and secondly, the mercury vapors will emit less UV light, and therefore the Bulb will burn dimmer.
The average life of fluorescent lamps 5 000-8 000 sec. Imported samples can have this figure, and reaching up to 10 000 hours.