A time for Modern Physics:(Please check the classical idea)

In the photoelectric experiments the photocurrent is proportional to the intensity of the light.Can this result alone be used to distinguish between the classical and quantum theories?

As I know, this feature of photoelectric effect is the only feture that is compatible with classical concepts.So,this cannot be used like that...

[Classical Idea: As you increase the intensity of the light,you are treating the free surface electrons with Electric field and magnetic field of bigger amplitude---Force on them is bigger and they can speed up more promptly giving a bigger value of photoelectric current.]

In the photoelectric experiments the photocurrent is proportional to the intensity of the light.As I recall from what little physics I was taught, this is wrong: the photocurrent depends only on the frequency, and not at all on the intensity. Isn't this the origin of the "light quantum" theory?

Then you are recalling something wrong.

Photocurrent (which is like the number of photoelectrons) depends on intensity.

maximum value of velocity of emitted electrons depends on frequency.

Ah, OK. Thank you for the correction.

Photocurrent (which is like the number of photoelectrons) depends on intensity. ...Generally true that one photon can give at most one photo-electric ejected electron, but not necessarily true if that photon is an x-ray. See:
http://en.wikipedia.org/wiki/Auger_electron

Then you can get more than one per photon. Not sure, but think two separate mechanisms may be at work. (I did not read the wiki article. -I only checked to make sure I had remembered "auger" correctly and not confused it with something else. Often wiki does not have it fully correct anyway.):

(1) Several already bound electrons can cascade down following the the X-ray ejecting an electron from the deep shell. For example, if X-ray make "hole" in the n =1 shell then that could be filled by a radiative transiton n=2 to 1, leaving a "hole" in the n= 2 shell, which could be filled from higher shell by another radiative transition etc. Effectively multipling the number of photons* and possibly the number of photoelectrons produced.

(2) The electron ejected by X-ray photoelectron can "hit" others and knock them out of the solid also.
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*Recognizing that solar photons can only give one photo electrons** and not very efficiently when they are liberated inside a photo-voltaic cell some have suggested "multiplying the solar photons" by first using them to heat*** some absorber in a vaccuum. This then becomes a hot body losing energy by radiation of IR photons (mainly). In pricinciple, you should be able to get twice as much current as the IR photons are a much better match to the band gaps in Silicon and Germanium used in solar cells. I.E. DOUBLE THE ENERGY OUTPUT. (Much more than twice if all the IR photons with less than band gap energy are reflected back to the hot absorber and not lost heat but that requires selective coating on the PC cells, which is more expensive than the PC cells - but what the heck, its only taxpayers money and they can afford to send man to Mars, so GWB thinks. :rolleyes:)

I think this might actually be an attractive idea for a space station**** as then the UV from the sun, which does not make it to the surface of the Earth, might be turned into 3 photons but do not think it has very been a competitive idea on Earth. (I just like it as it shows / requires good understanding of all this, including the solid state physics.)

**"Lifting" it from the "valance" to the "conduction" bands of a "band gap" semi-conductor, not ejecting it for the solid.

*** Possibly the only case were converting high quality energy to heat can improve efficiency of electric power generation. We should live near a "red giant" or God should have made some substance with bigger band gaps! He/She screwed up somewhere. :D

**** Vaccuum free also helps.

Continuing slightly off thread the "solar photon multiplying" idea of post 5:

Rather than spend space dollars available on sending man to Mars*, let’s do something to get non-polluting energy as follows:

Put in geo synchronous orbit (or low Earth orbit, if better, despite about half time in the dark) a lot of parabolic reflectors that send most of the solar energy striking them back to a relative small absorber at the focus. This absorber is well insulated (A few dozen layers of slightly wrinkled metal foil as it is in vacuum would be very light and excellent.) except for the solid angle which re-radiates IR back to the parabolic surface.

This surface has a selective coating that only transmits the IR with the band gap of the semi-conductor photovoltaic cells that are the next and final layer on the parabolic surface. Thus much of the IR radiated by the hot, solar heated absorber will keep returning along with the incident solar radiation until it is the correct wavelength to pass thru the selective surface and efficiently excite an election from the Photo Cell's "valance" band to the "conduction" band for collection as electric power.

Also note this "parabolic surface" is far from image quality - probably "fold out" rigid "petals" would be fine as the absorber target would be larger than typically used in solar thermal systems. (Perhaps with cross section of even 5% of the parabolic area.)

The electric power produced can be cheaply and efficiently converted to microwaves, perhaps using the same parabolic "off axis" to beam them down to Earth to a large "Retenna" under which sugar cane is growing near the Equator.**

I.e. an "all weather" solar energy system with about 5 times the efficiency of Earth based solar cells.
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*Nothing will come back from Mars that is worth 0.000,000,01 of the cost of bring it to earth, especially if man goes there. GWB seems to know no limit on how to foolishly spend the taxpayer’s money.

**Perhaps making aluminium in Brazil. Already makes a lot as has both Bauxite and cheap power. (93% is hydroelectric!)

Continuing slightly off thread the "solar photon multiplying" idea of post 5:

Rather than spend space dollars available on sending man to Mars*, let’s do something to get non-polluting energy as follows:

Put in geo synchronous orbit (or low Earth orbit, if better, despite about half time in the dark) a lot of parabolic reflectors that send most of the solar energy striking them back to a relative small absorber at the focus. This absorber is well insulated (A few dozen layers of slightly wrinkled metal foil as it is in vacuum would be very light and excellent.) except for the solid angle which re-radiates IR back to the parabolic surface.

This surface has a selective coating that only transmits the IR with the band gap of the semi-conductor photovoltaic cells that are the next and final layer on the parabolic surface. Thus much of the IR radiated by the hot, solar heated absorber will keep returning along with the incident solar radiation until it is the correct wavelength to pass thru the selective surface and efficiently excite an election from the Photo Cell's "valance" band to the "conduction" band for collection as electric power.

Also note this "parabolic surface" is far from image quality - probably "fold out" rigid "petals" would be fine as the absorber target would be larger than typically used in solar thermal systems. (Perhaps with cross section of even 5% of the parabolic area.)

The electric power produced can be cheaply and efficiently converted to microwaves, perhaps using the same parabolic "off axis" to beam them down to Earth to a large "Retenna" under which sugar cane is growing near the Equator.**

I.e. an "all weather" solar energy system with about 5 times the efficiency of Earth based solar cells.
-------
*Nothing will come back from Mars that is worth 0.000,000,01 of the cost of bring it to earth, especially if man goes there. GWB seems to know no limit on how to foolishly spend the taxpayer’s money.

**Perhaps making aluminium in Brazil. Already makes a lot as has both Bauxite and cheap power. (93% is hydroelectric!)

Billy T,

When you consider that NASA was formed, and remains today, as basically a military organization, then the fact that space science is financed as long as some military interest is satisfied, becomes understandable. This doesn't make it right, just understandable.

There are occasional socially interesting scientific crumbs spread around for public consumption of course. GWB is just an other pawn in the hame. You make a serioius judgement in werror when you conmsider that GWB is "foolishly" spending the taxpayers money. Look at it that GWB and his regime are doing exactly what they intend to be doing from a carefully constructed plan. It is only "foolish" if you take GWB at face value and consider him merely incompetant or misguided, as if he were actually working for the greater good for all and was just screwing up, instead his gang engages in the the greater good for the small numbers of commercial movers and shakers.

.

Iraq is a necessary part of the scheme, not to protect the US from Islamic terrorists, but to maintaiin a war footing and a distraction of the public from peaceful activities of government, things that don 't require the Lockheed-Martins of the country to suck us dry. Don't you think some probing of the Cydonian Plain on Mars would have some interesting possibilities to scrutinize??

Now that I have vented, with sincere apologies, but I just had to express it.
:shrug:

Billy T, When you consider that NASA was formed, ... but I just had to express it. :shrug:I think the fact that oil interests pay for GWB's campaigns is more of the reason why an idea that provides energy without oil or pollution is "dead on the ground" while GWB is in the white house. The Mars program will no doubt die after the election in the quagmire of debts. The Alcohol from corn program will be reduced naturally as the $0.54 / gallon tarriff is elimated. (Democrates are more concered that Joe American has cheap food, but even some couragous Republicants are already calling for that - McCane even did so in Iowa! - He has alway been couragous, even under torture in N. Vietnam prisoner camp.)

GWB knows that corn based alcohol will not significatly reduce oil consumption and is pushing for it to expanded his funding for Republicans amoung the wealthy of the agri-busness industry. GWB is carefull to state the goal is to "replace 20% of gasoline with alcohol" (by 2018, I think) and avoids stating anything about reducing oil imports. (Joe American wrongly assumes 20% replacement of gasoline is a 20% reduction in oil imports. - It is about a 2% reduction in oil imports, if any, and a great increase in Green House Gases, GHG, as Iowa's corn's requires lots of nitrogen fertalizer, which is converted to NO2 by bacteria etc in the soil. NO2 is a much worse GHG than CO2. Now GWB is alone in world as the agent blocking a functional GHG control system.)

Why was my post deleated?