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Laser Particle Speed?

SOG

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Actually I have been wondering, what are the Speed of Laser Particles? seems like a question that is not easy to answer? I mean is it possible for the light of laser actually go faster than the speed of light?

I did do some search on this Forum, and something like Quantum Physic comes up... Then I did a search in Google about it, some "Particle accelerator" comes up! ....

then I did another search on "laser is speed of light ?" One topic came up saying "Laser smashes light-speed record - physicsworld.com -
19 Jul 2000 ... But this speed limit has been smashed in a recent experiment in which a laser pulse travels at more than 300 times the speed of light (L J ..." but I was never able to find that Article...

so I don't know :confused: Anyone have Any idea at all ? I suppose Laser should have more power than normal lights, hence it should in some ways moves differently ? (If possible please keep it simple, I don't think alot of people understand Quantum Physic... but on the other hand, it seems hard to keep it simple :crackup::bowdown: )
 

Wolfman29

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Yeah, all lasers travel at C, the speed of light. If shined in a vacuum, it would be roughly 186,000 miles per second, or roughly 300,000 kilometers per second.
 

SOG

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I see... somehow I thought it will moves faster...

Thanks :D
 
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SOG

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But More photons = more power.... Um... OH, so it doesn't contribute to the speed factor! but then... um... so it's at speed of light...

but does different wave length affect the speed at all? I know it does affect the power in some ways (Which I also don't understand :p have something to do how other matters absorb/reflect different color ?) I mean the power which the laser have affect on matters.
 
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Wolfman29

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So the energy in a photon (a unit of light, which comprises lasers, as well), is based *not* on the speed of the photon, because they all travel at the same velocity, but the number of cycles it goes through a second, i.e. the frequency of the light, which is the same thing as the wavelength. The more cycles it goes through a second, i.e. the shorter the wavelength, the more energy it carries with it.

Thus, even though different wavelengths travel at the same speed, shorter wavelengths carry more energy per photon. That's why gamma rays will go through a mile of lead yet visible light will be reflected by a simple mirror.
 

SOG

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I see! Thanks for clear things out guys ! :D
 
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Maybe you should try and track down a high school physics book online or something similar that would be able to tie these concepts together for you. Intro textbooks usually explain things in pretty plain language. - Matt
 

SOG

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Maybe you should try and track down a high school physics book online or something similar that would be able to tie these concepts together for you. Intro textbooks usually explain things in pretty plain language. - Matt
They teaches the "dead ray" in high school books now? um... interesting... but the last time I actually read a book is quite a while ago... but I will certainly look at it again and see...

um... actually I did look for it online, but maybe my keywords wasn't right


:thanks::thanks:
 

SOG

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So the energy in a photon (a unit of light, which comprises lasers, as well), is based *not* on the speed of the photon, because they all travel at the same velocity, but the number of cycles it goes through a second, i.e. the frequency of the light, which is the same thing as the wavelength. The more cycles it goes through a second, i.e. the shorter the wavelength, the more energy it carries with it.

Thus, even though different wavelengths travel at the same speed, shorter wavelengths carry more energy per photon. That's why gamma rays will go through a mile of lead yet visible light will be reflected by a simple mirror.
By the way, if I remember correctly UV is more powerful than IR, IR is just heat... so does that mean purple laser is more powerful compare to red? :thinking: As it has shorter wavelength ? I mean powerful as in burning for examples paper and plastics
 
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RayBurne

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As weird as it seems, light power and photon energy are not the same. Since a photon is assumed to be a mass less particle that exhibit wave like features, its energy is completely dependent upon wavelength or frequency which is often called color for frequencies that the human eye can detect.
Power then represent the number of individual photons at each frequency all summed over a time period, let say a second. Therefore "power" always has a time component.
Wikipedia article on Watt is a fairly easy read on the subject.
 




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