A fluorescent lamp is a lightweight mercury vapor lamp that uses fluorescence to provide visible light. An electric current in the gas energizes the mercury vapor which gives off ultraviolet radiation through the discharge process and the ultraviolet rays radiate visible light to the phosphor coating of the inner wall of the lamp.
A fluorescent lamp converts electrical energy into useful light energy much more efficiently than incandescent lamps. The typical luminous efficiency of fluorescent lighting frameworks is 50 to 100 lumens per watt, which is a few times greater than the sufficiency of incandescent lamps with equivalent light output.
Fluorescent Lamp work:
- When we turn on the supply, the full voltage comes across the starter through the ballast along with the lamp. But at this time, there is no discharge, meaning no lumen output from the lamp.
- At this full voltage a glow discharge is first established in the starter. This is because the starter’s neon bulb has a much smaller electrode gap than a fluorescent lamp.
- The gas inside the starter is then ionized by this full voltage and heats the permanent magnet. This causes the permanent strip to bend to connect to the fixed contact.
- Now, current starts flowing through the starter. Although the ionization potential of neon is higher than that of argon, still due to the small electrode gap, a high voltage gradient appears in the neon bulb and hence the glow discharge starts first in the starter.
- As current begins to flow through the starter’s touched contacts of the neon bulb, the voltage across the neon bulb drops from the current, causing the voltage across the inductor (ballast) to drop. At low or no voltage across the starter’s neon bulb, the gas will no longer escape and therefore the permanent strip cools and separates from the fixed contact. When the contacts in the starter’s neon bulb break, the current is interrupted, and therefore at that point, a large voltage rises across the inductor (ballast).
- This high rated surge voltage is applied to the electrodes of the fluorescent lamp (tube light) and strikes the panning mixture (a mixture of argon gas and mercury vapor).
- The process of gas discharge starts and continues and hence the current again finds its way through the fluorescent lamp tube (tube light). The resistance offered by the gas during discharge of the panning gas mixture is less than the resistance of the starter.
- The emission of mercury atoms produces ultraviolet radiation which in turn exposes the phosphor powder coating to visible light rays.
- The starter is deactivated while the fluorescent lamp (tube light) is flashing because no current flows through the starter in this condition.