Light is a tag about anything generates photons in the visible spectrum
Questions tagged [light]
532 questions
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What are the little bits of metal that come out of light bulb filaments and why do they stick to only one terminal?
Recently I changed the headlights in my car and took a few micrographs of the filaments. A couple composite photos of old bulbs:
For reference, here's a new bulb filament:
On the left wire in the images of the old bulbs, there are many metal…
rsaxvc
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Does turning a lighbulb on and off repeatedly use more energy than just leaving it on for hours?
Let's say I have a 60W bulb in a lamp in my bedroom. If I kept the lamp on for 2 hours straight but the next day, I switched it on and off 10 times in intervals of 5 minutes. Which scenario would use more energy?
Christopher Chipps
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If Infrared not visible, why the red LEDs?
If infrared light is not visible to the human eye, why do most tv remote controls and security cameras appear to have a visible red colored LED lit when the infrared light is being emitted?
Is that visible red light present as a convenience…
dtmland
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Can I turn Radio waves into light?
Wikipedia says that the frequency of light is 300 THz.
I've made a radio waves transmitter that transmits about 100 MHz.
If I increase the frequency of the transmitter to 300 THz, will the antenna produce spark or light ?
Can I do this circuit…
Michael George
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Do "blown" fluorescent lights still use electricity?
When a fluorescent light fixture goes out, it often flickers and then after a while stops shining altogether. When this happens and when it finally dies is the circuit broken and does it still use electricity?
I don't understand too much what…
PressingOnAlways
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Why are Edison screws allowed to be used?
Why are the Edison screws allowed to be used? They seem unsafe. Why are they designed that way?
They require a complete grounding system to ground devices for the rare situation where the hot wires somehow touches the metal case of the device
While…
Ronen Festinger
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Why are there only RGB and RGBW-LEDs, but none with more chips inside one housing?
In another thread the question emerged, where the LEDs with 5 or more dies of different colours are. (Kudos to Brian Drummond) The background is as follows:
RGB LEDs are very popular for creating colourful lighting effects. In fact, due to the three…
Ariser
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Is it possible to generate light with an antenna?
An antenna (e.g. a dipole) is able to radiate at a certain frequency thanks to the EM field generated by a current provided by a signal generator at such a frequency.
So, for instance:
Voltage source at frequency f (representing an amplifier) +…
Kinka-Byo
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Why does an LED have to be a diode?
I know LED stands for Light Emitting Diode; but why does this component need to be a diode to emit light?
My question assumes that the "leds" we see everywhere (for lighting, screens, etc) are actually diodes -- this assumption might be wrong.
noamtm
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How do filament LED bulbs work, looking very similar to incandescent bulbs?
Filament LED bulbs use very narrow strips containing the LED,
which look similar to filaments of an old incandescent bulb:
They look like a normal bulb with large "old-style" coal filaments, and are of about the same size and shape as the common…
Volker Siegel
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Lumens specs when buying a flashlight/torch. Why maglite has only 680lm but cheap ones have 900,000?
I am working as a night delivery driver and when its dark and/or rainy it's almost impossible to read many of the house numbers/names I am looking for.
I've heard of Maglite and in fact my friend has a large Maglite which is 680lm and very powerful…
Big T Larrity
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Light bulb burns out -- why there is an arc in the switch?
I use light bulbs (common incandescent) in the room and they
burn out periodically, ca. one bulb in 4 months burns out.
Very often, exactly at the moment when it happens, I see an arc (blueish light flash) in the switch, so the bulb always burns…
Mikhail V
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Can antennas be viewed as light sources?
Clearly antennas are nothing but a device to radiate the electrical energy through electromagnetic waves.
Since visible light is also simply a certain range of frequencies, isn't it more easier to think of antennas as different shapes of "light"…
Vishwa Mithra Tatta
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How does a fire detector distinguishes between smoke particles and others?
Many fire detectors are optic so that when smoke comes in the fire detector, it causes the light from LED reflect to the photodiode.
But the question is why don't they alarm when somebody takes a warm bath or when somebody is dust removing? What is…
user24478