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In visual perception, flicker is a human-visible change in luminance of an illuminated surface or light source which can be due to fluctuations of the light source itself, or due to external causes such as due to rapid fluctuations in the voltage of the power supply (power-line flicker) or incompatibility with an external dimmer.
The requirements of a flicker measurement equipment are defined in the international electro-technical standard IEC 61000-4-15. [2]A flickermeter is composed of several function blocks which simulate a 230 V/60 W or a 120 V/60 W incandescent lamp (reference lamp) and the human perception system (eye-brain model).
An open (single envelope) CFL [12] An encapsulated/closed (double envelope) CFL. Some fluorescent lamps emit ultraviolet radiation. [citation needed] The Health Protection Agency of the United Kingdom has conducted research concluding that exposure to open (single envelope) compact fluorescent lamps (CFLs) for over 1 hour per day at a distance of less than 30 cm can exceed guideline levels as ...
Using an amalgam with some other metal reduces the vapor pressure and increases the optimum temperature range. The bulb wall "cold spot" temperature must still be controlled to prevent condensing. High-output fluorescent lamps have features such as a deformed tube or internal heat-sinks to control cold spot temperature and mercury distribution.
A diamond may begin to glow while being rubbed; this occasionally happens to diamonds while a facet is being ground or the diamond is being sawn during the cutting process. Diamonds may fluoresce blue or red. Some other minerals, such as quartz, are triboluminescent, emitting light when rubbed together. [19]
A flicker light bulb, flicker flame light bulb or flicker glow lamp is a gas-discharge lamp which produces light by ionizing a gas, usually neon mixed with helium and a small amount of nitrogen gas, by an electric current passing through two flame shaped electrode screens coated with partially decomposed barium azide. The ionized gas moves ...
With HMI bulbs, color temperature varies significantly with lamp age. A new bulb generally will output at a color temperature close to 15,000 K during its first few hours. As the bulb ages, the color temperature reaches its nominal value of around 5600 K or 6000 K. With age, the arc length becomes larger as more of the electrodes burn away.
Light bulbs using coiled coil filaments are sometimes referred to as 'double-coil bulbs'. For a 60-watt 120-volt lamp, the uncoiled length of the tungsten filament is usually 580 millimetres (22.8 in), [ 76 ] and the filament diameter is 0.046 millimetres (0.0018 in).