Author Topic: Stan and dislodging electrons with ledlight ( Photoelectric Effect)  (Read 8576 times)

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Hi,

Here an article about dislodging electrons with help of LEDS.



In 20th century physics two ideas stand out as being totally revolutionary: relativity and quantum theory. Although Einstein is best known for his theory of relativity, he also played a major role in developing quantum theory. And it was his contribution to quantum theory - explaining the photoelectric effect - which won Einstein his Nobel Prize in 1921.

The photoelectric effect is the name given to the observation that when light is shone onto a piece of metal, a small current flows through the metal. The light is giving its energy to electrons in the atoms of the metal and allowing them to move around, producing the current. However, not all colours of light affect metals in this way. No matter how bright a red light you have, it will not produce a current in a metal, but even a very dim blue light will result in a current flowing. The problem was that these results can't be explained if light is thought of as a wave. Waves can have any amount of energy you want - big waves have a lot of energy, small waves have very little. And if light is a wave, then the brightness of the light affects the amount of energy - the brighter the light, the bigger the wave, the more energy it has. The different colours of light are defined by the amount of energy they have. If all else is equal, blue light has more energy than red light with yellow light somewhere in between. But this means that if light is a wave, a dim blue light would have the same amount of energy as a very bright red light. And if this is the case, then why won't a bright red light produce a current in a piece of metal as well as a dim blue light? Einstein realised that the only way to explain the photoelectric effect was to say that instead of being a wave, as was generally accepted, light was actually made up of lots of small packets of energy called photons that behaved like particles. Einstein wasn't the first person to use the idea of photons, but he was the first to make it the starting point of an explanation rather than a convenient fiddle to explain away odd results.

With light as photons, Einstein showed that red light can't dislodge electrons because its individual photons don't have enough energy - the impacts are just not large enough to shift the electrons. However, blue light can dislodge electrons - each individual photon has more energy than the red photon. And photons of ultraviolet light, which have yet more energy, will give electrons enough energy to whizz away from the metal altogether. A good way to think of the photoelectric effect is like a full car park with lots of really bad drivers. There is a car parked in a space, and lots of other drivers want that space. To get it they can try knocking the parked car out of the way, but they can only manage to hit it one car at a time. A tiny red mini just won't have the energy to knock the parked car out of the parking space, but a big blue van will. And imagine hitting the parked car with a big ultraviolet lorry - the parked car is most likely going to move far enough to collide with something else. Returning to light and electrons, there is never really just one photon of light at a time. A bright light emits lots of photons, but it doesn't matter how bright a red light gets; red photons will still not be able to budge a single electron. This is like having a car park full of red minis each randomly hitting a parked car in turn - there will be a lot of dents but the parked car will remain where it is. However, even a dim blue light will shift some electrons - we know that even one blue van will be able to move the parked car.

Einstein's explanation of the photoelectric effect was just the start of an avalanche of discoveries that became quantum theory. In this theory, light is not just a particle and not just a wave: it can be one or the other, depending on how it is measured. And it was discovered later that even the electrons are not just particles but are waves too.

http://www.einsteinyear.org/facts/photoelectric_effect/

br
Steve

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #1 on: December 22, 2010, 07:18:17 am »
(reply corrected)
more information to compliment the above:

the photo electric effect ( http://en.wikipedia.org/wiki/Photoelectric_effect ) is the reason why tesla's invention worked, this tesla invention (image below) used to be featured on wikipedia's photoelectric effect page (now not used at all anymore) along with information with it. the electrons would be disloged by blue and UV "radiant energy" (now called light, shown in yellow in the image) and the metal plate would become positively charged.  the earth is a large electronsink and electrons from the earth would be attracted to the plate and thus the motor would work.


now. what about gases?
well i ask you to look up pages about ionisation, you will find light can trigger it, pulsed or constant is better? i dont know. led may go dimmer if allowed to be hotter. (reply 6 links the above two)

light reading:
http://www.stockeryale.com/i/leds/lit/app001.htm (Pulsed Operation of LED Illuminators - do note that the average power is the rated power of leds)
http://en.wikipedia.org/wiki/Ionization
http://en.wikipedia.org/wiki/Photoionization
http://www.chemistryland.com/CHM130W/10-ModernAtom/Spectra/ModernAtom.html (image source)
http://commons.wikimedia.org/wiki/File:PhotoelectricEffect%28Tesla%29.png (image source)

excerpt of removed text (after describing what tesla thought):
In practice, a polished insulated metal plate or other  conducting-body in radiant energy (e.g. sunlight) will gain a positive  charge as electrons are emitted by the plate. As the plate charges  positively, electrons form an electrostatic force on the plate (because  of surface emissions of the photoelectrons), and "drain" any  negatively charged capacitors. In his patent application, Tesla noted  that as the rays or radiation fall on the insulated conductor (which is  connected to a capacitor), the capacitor will indefinitely charge electrically.

have fun,
Charlie.

ps, steve, when i modify the message it seems to delete it unless i click the second Modify message button which does the text section only!
« Last Edit: December 23, 2010, 00:21:22 am by charlieb000 »

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #2 on: December 22, 2010, 13:29:49 pm »
Does not the photoelectric effect, in fact ionize the atoms through electron ejection? Please correct me if I misunderstood. You claim the text above outlining the photoelectric effect is not related to Meyer and then prove his statement true with your rebuttal? The response was perfect up to the point where the relation to Meyer comes to play. I fail to see the main point? Light is just electromagnetic energy at a certain voltage potential and frequency.

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #3 on: December 22, 2010, 13:54:05 pm »
I think the link with Meyer is the ionization part. Meyer describes 2 options to ionize his ambient air or whatever he wanted to ionize.

One was with high voltage and the otheone was with laser and metal. Not sure how much power his leds had to be to get the same results as with hv....


Steve

Ps
I will have a look at that forum issue Charlie.

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #4 on: December 22, 2010, 21:44:32 pm »
Does not the photoelectric effect,....

this is what i am pointing out and you did miss it: the photoelectric effect pertains to removing electrons (completely) from the surface - be it steel or whatever. ionization is making electrons shift to an orbit that is further away - when they go back light (even Xrays in some cases) is emitted, this is how flurescent lamps work.

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #5 on: December 22, 2010, 23:01:17 pm »
Ok, sorry for the confusion. Why does Stan often state that electrons are removed or ejected from the gases?

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #6 on: December 23, 2010, 00:04:01 am »
Ok, sorry for the confusion. Why does Stan often state that electrons are removed or ejected from the gases?


firstly i have to correct myself and possibly rewrite what i have written, which will perhaps make both of these the result of the same effect - i didnt pick up that gases get ionised while metals get charged. ionisation is when the electron leaves the nucleus, so you are right, and i was confused, because steve's explanation lacked info on incrimental steps, light emmission and only talked about metals rather than hydrogen, the tesla patent came to mind and i thought i needed to add stuff about hydrogen.

when the hydrogen electron recieves a specific amount of light energy (photoionization) and/or electrical energy (field ionization) to excite the electron it will incrementally go to higher orbits and if it recieves a high enough energy it will leave, according to a text book i have, this is 13.6eV (electron volts).

the oxygen atom can emit xrays, i think.



http://science.jrank.org/pages/3679/Ion-Ionization.html (terms)
« Last Edit: December 23, 2010, 00:46:12 am by charlieb000 »

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Re: Stan and dislodging electrons with ledlight ( Photoelectric Effect)
« Reply #7 on: December 23, 2010, 01:12:08 am »
Yes, it is confusing isn't it? I wonder if it's meant to be that way? lol! I do know they commercially manufacture UV spectrum lights that are used for creating ozone, I have also read of microwave ionizers that can  create ozone in adjacent rooms through walls. So, it would seem that a particular atom, such as oxygen, would have several resonant frequencies throughout  the entire electromagnetic spectrum including sound, ultrasound, radio, visible light, microwave, and so on. Harmonics perhaps?