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A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor coating in the lamp glow.
New lighting systems have not used magnetic ballasts since the turn of the century, however some older installations still remain. Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz (twice of the utility frequency; the lamp is lit on both the positive and negative half-wave of a cycle).
At light intensities used in single-molecule fluorescence imaging (0.1-1 kW/cm 2 in typical experimental setups), even most robust fluorophores continue to emit for up to 10 seconds before photobleaching in a single step. For some dyes, lifetimes can be prolonged 10-100 fold using oxygen scavenging systems (up to 1000 seconds with optimisation ...
Not all of the light is absorbed, and a small portion of the 520 nm laser light transmits through the top, unaltered by the ruby's red color. Fluorescence occurs when an excited molecule, atom, or nanostructure , relaxes to a lower energy state (usually the ground state ) through emission of a photon without a change in electron spin .
The 2023-24 drive recycled 2,218 pounds of string lights. Neenah was the leader with 510 pounds, followed by Oshkosh with 340 pounds and Fox Crossing with 266 pounds.
A preheat fluorescent lamp circuit using automatic starting switch. A: Fluorescent tube, B: Power (+220 volts), C: Starter, D: Switch (bi-metallic thermostat), E: Capacitor, F: Filaments, G: Ballast. When power is first applied to the circuit, there will be a glow discharge across the electrodes in the starter lamp.
Circular and U-shaped lamps were devised to reduce the length of fluorescent light fixtures. The first fluorescent light bulb and fixture were displayed to the general public at the 1939 New York World's Fair. The spiral CFL was invented in 1976 by Edward E. Hammer, an engineer with General Electric, [7] in response to the 1973 oil crisis. [8]
The high output frequency of an electronic ballast refreshes the phosphors in a fluorescent lamp so rapidly that there is no perceptible flicker. The flicker index, used for measuring perceptible light modulation, has a range from 0.00 to 1.00, with 0 indicating the lowest possibility of flickering and 1 indicating the highest.