![]() Most of the photons that are released from the mercury atoms have wavelengths in the ultraviolet (UV) region of the spectrum, predominantly at wavelengths of 253.7 and 185 nanometres (nm). This higher energy state is unstable, and the atom will emit an ultraviolet photon as the atom’s electron reverts to a lower, more stable, energy level. Tightening the choke’s screws may instantly eliminate the problem. The reason for this lies in the loosely fitted choke on to the fixture which vibrates in accordance with the 50 or 60-hertz frequency of our AC mains and creates a humming sort of noise. After this, the choke only acts like a low impedance current limiter to the tube as long as the light is kept illuminated.Ī common problem associated with these types of fixtures is humming or buzzing.If the tube does not sufficiently charge up, subsequent kicks are delivered by the choke due to rapid switching of the starter, so that finally the tube strikes.At this point, the ballast or choke “kick’s back” it’s stored current, which again passes through the filaments and ignites the tube light once again.However, now that the heat from the light is gone, the bimetallic strip cools and bends away from the electrode, opening the circuit again. This stops the charged particles from creating the electrical arc that created light. This creates a light, however, the heat from the bulb causes one of the electrodes (a bimetallic strip) to bend, making contact with the other electrode. When electricity passes through it an electrical arc is created between the two electrodes. The starter is made up of a discharge bulb with two electrodes next to it. The filaments light up and instantly warm up the tube.When an AC voltage is applied to a tube light fixture, the voltage passes through the choke, the starter, and the filaments of the tube.This principle of the choke is exploited in lighting a fluorescent tube light. An inductor by nature always has a tendency to throw back the stored current in it, every time the power through it is switched OFF.It consists of a long copper winding over iron laminations. The choke is, in fact, a large inductor.Once the conduction of electrons between the electrodes is complete, no more heating of the filaments is required and the whole system works at a much lower current. When exposed to the ultraviolet light, the particles emit a white light which we can see. Phosphors will give off light when exposed to light. This is why the tube was coated with phosphorous. However, the light they emit is ultraviolet, and not visible to the naked eye, so another step needs to take place before we can see the light. ![]() As electrons return to their original energy level, they begin to release light. Electrons then collide with the gaseous mercury atoms, increasing the amount of energy. The energy also converts some of the mercury from a liquid to a gas.The process initially requires a relatively high amount of power. These electrode filaments are used to preheat the tube and initiate rapid conduction of electrons between the two end electrodes.The tube is then finally sealed at low pressure with two filament electrodes each at its both ends.Its inner surface is coated with phosphorous and is filled with inert gas, generally argon, with a trace of mercury. A fluorescent lamp basically consists of a long glass gas discharge tube.
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