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When a user is logging on to Windows, the startup sound is played, the shell (usually EXPLORER.EXE) is loaded from the [boot] section of the SYSTEM.INI file, and startup items are loaded. In all versions of Windows 9x except ME, it is also possible to load Windows by booting to a DOS prompt and typing "win".
Macs made after 1987 but prior to 1998, upon failing the POST, will immediately halt with a "death chime", which is a sound that varies by model; it can be a simple beep, a car crash sound, the sound of shattering glass, a short musical tone, or more. On the screen, if working, will be the Sad Mac icon, along with two hexadecimal strings, which ...
Typical test automation features usually apply to loss testing applications, and include: The ability to set the unit to read 0 dB at a reference power level, typically the test source. The ability to store readings into internal memory, for subsequent recall and download to a computer.
The luminous efficacy of the source is a measure of the efficiency of the device with the output adjusted to account for the spectral response curve (the luminosity function). When expressed in dimensionless form (for example, as a fraction of the maximum possible luminous efficacy), this value may be called luminous efficiency of a source ...
If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam, then the beam would have a luminous intensity of 1 candela. If the optics were changed to concentrate the beam into 1/2 steradian then the source would have a luminous intensity of 2 candela.
The whole detailed discussion about lumen output of 120V vs 230V lamps is off-topic for this page defining and discussing lumen. Take it to a luminous efficacy page, if there is one. Here just give an example like a "typical" candle at about 10 lm, a 100W bulb at about 1500 lm, a streetlight at 20,000-50,000 lm.
Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp. Lamp types include: Ballast : A ballast is an auxiliary piece of equipment designed to start and properly control the flow of power to discharge light sources such as fluorescent ...
Lumen maintenance is the most useful gauge to determine the lifetime or useful light output rating of an LED light source. Unlike traditional light sources such as incandescent lamps, LEDs rarely fail outright and instead continue to emit light, albeit at slowly diminishing rate over time. [ 1 ]