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Magnets + Lasers?
- Thread starter nikokapo
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i have a question:
i have a dimmer switch on my room (it makes my light go from 0 to 220v. as i turn the wheel)
if it's like 1/4 turned, light is very dim and it makes like a 17kHz sound, very annoying. anybody know why? (when i turn the wheel a little more and take it to its max. the sound disappears, i bet it's because it reaches 24kHz and goes further so i cant hear it)
i have a dimmer switch on my room (it makes my light go from 0 to 220v. as i turn the wheel)
if it's like 1/4 turned, light is very dim and it makes like a 17kHz sound, very annoying. anybody know why? (when i turn the wheel a little more and take it to its max. the sound disappears, i bet it's because it reaches 24kHz and goes further so i cant hear it)
nikokapo said:
Why do I sense that you already know the answer to this question…
. I believe (not sure), that there is a transformer inside which dissipates the unused voltage into heat and vibration, like a speed-sensitive drill makes the annoying squeaking sound when not at full power. My ESC on my rc toys do the same thing. Electric vehicles do it too. However, these units in lieu of a light use a motor so like a titer-totter (power/motor or power/light) needs "back pressure", or resistance. Similar to a valve on a sink, sometimes makes more noise when it isn't fully open. I'm sure there is a much more detailed scientific explanation for this but since this thread has been so interesting I couldn't resist. ;DAttachments
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nikokapo said:
AFAIK, I don't believe scientifical is a word, how about trying scientific.
Second if I remember my basic high school physics and other courses from 20 years ago, photons are wavicles (which actually IS a word)
This is the first reference I found:
http://twistedphysics.typepad.com/cocktail_party_physics/2007/11/the-photon-has-.html
In principle, every time you walk by a laser or any other object moves in relation to the beam, it puts a gravitational force on the beam bending it very slightly (unobservable obviously). If you were a really big person (say the size of the sun) and you occupied the space of a basketball. ie: If the mass of an object exceeds it's ability on an atomic level to support that mass physically, you would collapse into a black hole and then you could bend anything including light to the point that nothing could escape.
The only reason you "Stick" to the earth is not only the earth having gravity, but YOU also have a gravitational pull. The two act similarly to magnets (but you are obviously the weaker one)
That's my understanding in basic english.
This principle is just like many others that have to be carried to an extreme in order to actually have any real effect on things.
Another similar one is the Time dilation effect. That one will get you really to thinking.
Basically it says that the faster you move the slower time goes. But in a weird forumla taking the square root of the following: one minus your velocity squared over the speed of light squared. (ie: sq rt of 1-(v*v/c*c))
Another high school phyics formula! Have fun with that!
http://www.epanorama.net/documents/lights/lightdimmer.html#basics
Power harmonics caused by dimmers
All phase control dimmers are non-linear loads. A non-linear load is one where current is not in proportion to voltage. The non-linear load on dimming systems is caused by the fact that current is switched on for only part of the line cycle by a phase control dimming system. This non-linear load creates harmonic distortion on the service feeder.
Harmonics are currents that occur at multiples of the power line voltage frequency. In Europe where line frequency is 50 Hz the 2nd harmonic frequency is 100 Hz; the 3rd harmonic is 150 Hz, and so on. In North America where line frequency is 60 Hz the 2nd harmonic frequency is 120 Hz; the 3rd harmonic is 180 Hz, and so on.
Excess harmonic currents cause conductors and the steel cores of transformers and motors to heat. Odd-order harmonic currents (specifically the 3rd harmonic) add together in the neutral conductor of 3 phase power distribution systems. The 3rd order harmonic current present on the neutral is the arithmetic sum of the harmonic current present on the three phase conductors (this also applies to the 9th, the 15th and so on harmonics). Harmonics could theoretically elevate the neutral current to 3.0 times what is present on a phase conductor. With typical phase control dimming system connected to three pahse feed, the harmonics normally elevate neutral current to about 1.37 times phase current. If the wires are not properly rated for this, neutral conductor overheating or unexplained voltage drops can occur in large dimming systems.
Sometimes the heating of the distribution trasformer can be a problem, because transformers are rated for undistorted 50 Hz or 60 Hz load currents. When load currents are non-linear and have substantial harmonic content, they cause considerably more heating than the same undistorted current. In heavily dimmed system, you might not be able to ultilize more than around 70 % of the rated transformer power rating because of harmonic induced heating. Additionally, transformers used to feed dimming systems are subjected to stress because of cold lamp inrush currents (can be up to 25 times normal current). Inrush currents and harmonics can drastically reduce the service life of the service transformer.
Eliminating the effects of harmonic currents in large light dimmer systems normally requires oversizing neutral conductors and derating the service transformer.
In a normal low power light dimmer case you don't have to woryr much about the harmonics and transformer loads, because the light load of few hundred watts is clearly just a small fraction of the total transformer load.
Buzzing problems with dimmers
Each good dimmer has a filter choke inside. Those chokes help to filter out electrical noise that often causes hum to be picked up in sound system and musical instrument pick-ups. The slower the current rise is, the less noise is picked by sound system.
The chokes also help to eliminate 'lamp singing' that can cause audible noise to come from the lighting fixtures. Lamps with power rating of 300W or more tend to more or less acoustic noise when dimmed. If this acoustic noise is a problem can be removed by adding a series coil which limits the current rise time to around 1 millisecond.
In providing those filtering functions, the chokes themselves can generate a slight buzz. Fast current changes in the coil can make the coil wiring and core material easily vibrate which causes buzzing noise. A little bit of buzzing is normal with filtered dimmers. If the buzz from dimmer can be a problem it is recommended that the dimmer is placed in the area where this buzz will not be a problem.
As far as the 'bulb singing' concerned, a bulb consists of a series of supports and, essentially, fine coils of wire. When the amount of current flow abruptly changes the magnetism change can be much stronger than it is on a simple sine wave. Hence, the filaments of the bulb will tend to vibrate more with a dimmer chopping up the wave form, and when the filaments vibrate against their support posts, you will get a buzz. If you have buzzing, it's always worth trying to replace the bulb with a different brand. Some cheap bulb brands have inadequate filament support, and simply changing to a different brand may help.
Buzzing bulbs are usually a sign of a "cheap" dimmer. Dimmers are supposed to have filters in them. The filter's job is to "round off" the sharp corners in the chopped waveform, thereby reducing EMI, and the abrupt current jumps that can cause buzzing. In cheap dimmers, they've economized on the manufacturing costs by cost-reducing the filtering, making it less effective.
In very high power dimming systems the wiring going to lighting can also cause buzzing. The fast current makes the electrical wiring to vibrate a little bit and if the wire is installed so that the vibration can be transferred to some other material then the buzzing could be heard. The buzzing caused by the vibration of the wiring is only problem in very high power systems like theatrical lighting with few kW of lights connected to the same cable. Better filtered dimmers can reduce the problem because the filter makes the current changes slower so the wires make less noise.
Why does dimmed lighting sometimes hum, and how can it be corrected?
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
Power harmonics caused by dimmers
All phase control dimmers are non-linear loads. A non-linear load is one where current is not in proportion to voltage. The non-linear load on dimming systems is caused by the fact that current is switched on for only part of the line cycle by a phase control dimming system. This non-linear load creates harmonic distortion on the service feeder.
Harmonics are currents that occur at multiples of the power line voltage frequency. In Europe where line frequency is 50 Hz the 2nd harmonic frequency is 100 Hz; the 3rd harmonic is 150 Hz, and so on. In North America where line frequency is 60 Hz the 2nd harmonic frequency is 120 Hz; the 3rd harmonic is 180 Hz, and so on.
Excess harmonic currents cause conductors and the steel cores of transformers and motors to heat. Odd-order harmonic currents (specifically the 3rd harmonic) add together in the neutral conductor of 3 phase power distribution systems. The 3rd order harmonic current present on the neutral is the arithmetic sum of the harmonic current present on the three phase conductors (this also applies to the 9th, the 15th and so on harmonics). Harmonics could theoretically elevate the neutral current to 3.0 times what is present on a phase conductor. With typical phase control dimming system connected to three pahse feed, the harmonics normally elevate neutral current to about 1.37 times phase current. If the wires are not properly rated for this, neutral conductor overheating or unexplained voltage drops can occur in large dimming systems.
Sometimes the heating of the distribution trasformer can be a problem, because transformers are rated for undistorted 50 Hz or 60 Hz load currents. When load currents are non-linear and have substantial harmonic content, they cause considerably more heating than the same undistorted current. In heavily dimmed system, you might not be able to ultilize more than around 70 % of the rated transformer power rating because of harmonic induced heating. Additionally, transformers used to feed dimming systems are subjected to stress because of cold lamp inrush currents (can be up to 25 times normal current). Inrush currents and harmonics can drastically reduce the service life of the service transformer.
Eliminating the effects of harmonic currents in large light dimmer systems normally requires oversizing neutral conductors and derating the service transformer.
In a normal low power light dimmer case you don't have to woryr much about the harmonics and transformer loads, because the light load of few hundred watts is clearly just a small fraction of the total transformer load.
Buzzing problems with dimmers
Each good dimmer has a filter choke inside. Those chokes help to filter out electrical noise that often causes hum to be picked up in sound system and musical instrument pick-ups. The slower the current rise is, the less noise is picked by sound system.
The chokes also help to eliminate 'lamp singing' that can cause audible noise to come from the lighting fixtures. Lamps with power rating of 300W or more tend to more or less acoustic noise when dimmed. If this acoustic noise is a problem can be removed by adding a series coil which limits the current rise time to around 1 millisecond.
In providing those filtering functions, the chokes themselves can generate a slight buzz. Fast current changes in the coil can make the coil wiring and core material easily vibrate which causes buzzing noise. A little bit of buzzing is normal with filtered dimmers. If the buzz from dimmer can be a problem it is recommended that the dimmer is placed in the area where this buzz will not be a problem.
As far as the 'bulb singing' concerned, a bulb consists of a series of supports and, essentially, fine coils of wire. When the amount of current flow abruptly changes the magnetism change can be much stronger than it is on a simple sine wave. Hence, the filaments of the bulb will tend to vibrate more with a dimmer chopping up the wave form, and when the filaments vibrate against their support posts, you will get a buzz. If you have buzzing, it's always worth trying to replace the bulb with a different brand. Some cheap bulb brands have inadequate filament support, and simply changing to a different brand may help.
Buzzing bulbs are usually a sign of a "cheap" dimmer. Dimmers are supposed to have filters in them. The filter's job is to "round off" the sharp corners in the chopped waveform, thereby reducing EMI, and the abrupt current jumps that can cause buzzing. In cheap dimmers, they've economized on the manufacturing costs by cost-reducing the filtering, making it less effective.
In very high power dimming systems the wiring going to lighting can also cause buzzing. The fast current makes the electrical wiring to vibrate a little bit and if the wire is installed so that the vibration can be transferred to some other material then the buzzing could be heard. The buzzing caused by the vibration of the wiring is only problem in very high power systems like theatrical lighting with few kW of lights connected to the same cable. Better filtered dimmers can reduce the problem because the filter makes the current changes slower so the wires make less noise.
Why does dimmed lighting sometimes hum, and how can it be corrected?
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
As far as the 'bulb singing' concerned, a bulb consists of a series of supports and, essentially, fine coils of wire. When the amount of current flow abruptly changes the magnetism change can be much stronger than it is on a simple sine wave. Hence, the filaments of the bulb will tend to vibrate more with a dimmer chopping up the wave form, and when the filaments vibrate against their support posts, you will get a buzz. If you have buzzing, it's always worth trying to replace the bulb with a different brand. Some cheap bulb brands have inadequate filament support, and simply changing to a different brand may help.
Buzzing bulbs are usually a sign of a "cheap" dimmer. Dimmers are supposed to have filters in them. The filter's job is to "round off" the sharp corners in the chopped waveform, thereby reducing EMI, and the abrupt current jumps that can cause buzzing. In cheap dimmers, they've economized on the manufacturing costs by cost-reducing the filtering, making it less effective.
&
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
was the answer i was looking for.
you did it again, ace!
THANK YOU
Buzzing bulbs are usually a sign of a "cheap" dimmer. Dimmers are supposed to have filters in them. The filter's job is to "round off" the sharp corners in the chopped waveform, thereby reducing EMI, and the abrupt current jumps that can cause buzzing. In cheap dimmers, they've economized on the manufacturing costs by cost-reducing the filtering, making it less effective.
&
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
was the answer i was looking for.
you did it again, ace!
THANK YOU
icecruncher said:
The even more complicated part is that the time dilation is relative to inertial reference frames. If you are on a train moving at some high fraction of the speed of light you will measure time normally, but the clock you see as you pass by will appear to be going more slowly. Also, the guy sitting next to that clock will see the clock tick normally while he sees your clock moving more slowly. This is the source of the twin paradox where one twin is on a space ship travelling near the speed of light and returns at a later time. Which twin is older..... (and one of them is older.)
it's kind of a trick question. special relativity which has much much more simple equations can't explain this case. SR requires that all objects in question be in an inertial reference frame, or a frame of reference in which there is no acceleration. The twin in the spaceship at some point has to turn around so that implies an acceleration and thus no inertial reference frame. This means that you have to use general relativity which requires a lot of disgusting tensor calculations. The twin on earth is also accelerating, but because our velocity is so small compared to c that the effects are minute. So finally we get that the twin on the ship has aged less than the twin that stayed on earth.
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climbak said:
Reason I brought this up, is that if photons were truly a particle in all senses of the word they would violate the formula and exist entirely out of time. The formula would solve for a photon "Particle" as time to the sq rt of 0.
I just wanted to share this since it reminded me of this thread. Apperently, this guy can "hear" the sound of electric current. :-? http://www.laserpointerforums.com/forums/YaBB.pl?num=1210152418/15
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