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Photoelectric Emission - Help? - HSN forum

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Photoelectric Emission - Help?


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#1 jambo david

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Posted 23 April 2006 - 03:07 PM

I'm really confused about how it works. I don't suppose anyone has time for a little explanation?

p.s. Do you guys get paid for helping us?

#2 gsmushet1

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Posted 23 April 2006 - 10:13 PM

QUOTE(jambo david @ Apr 23 2006, 04:07 PM) View Post

I'm really confused about how it works. I don't suppose anyone has time for a little explanation?

p.s. Do you guys get paid for helping us?


Well the electrons that orbit an nuclues do so at different heights from the nucleus known as "energy levels". Each level has a particular energy assigned to it. When a photon that has energy equal to the energy difference of two levels becomes incident on the atom then an electron on that level is given enough energy to move up another energy level(into excited state). If an electron in the excited state is given even more energy, then it is given enough energy to be released from the atom and is then known as a "photoelectron" which has just undergone "photoelectric emission".

I don't think they get paid:S..i'm just a random guy, not involved with the site in anyway.

#3 jambo david

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Posted 24 April 2006 - 03:19 PM

QUOTE(gsmushet1 @ Apr 23 2006, 11:13 PM) View Post

QUOTE(jambo david @ Apr 23 2006, 04:07 PM) View Post

I'm really confused about how it works. I don't suppose anyone has time for a little explanation?

p.s. Do you guys get paid for helping us?


Well the electrons that orbit an nuclues do so at different heights from the nucleus known as "energy levels". Each level has a particular energy assigned to it. When a photon that has energy equal to the energy difference of two levels becomes incident on the atom then an electron on that level is given enough energy to move up another energy level(into excited state). If an electron in the excited state is given even more energy, then it is given enough energy to be released from the atom and is then known as a "photoelectron" which has just undergone "photoelectric emission".

I don't think they get paid:S..i'm just a random guy, not involved with the site in anyway.

Thanks, so does the photon that's causing the stimulated emission get absorbed or does it bounces off

#4 gsmushet1

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Posted 24 April 2006 - 05:49 PM

It is destroyed as all of it's energy is given to the electron in the form of kinetic energy.

#5 jambo david

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Posted 24 April 2006 - 05:53 PM

QUOTE(gsmushet1 @ Apr 24 2006, 06:49 PM) View Post

It is destroyed as all of it's energy is given to the electron in the form of kinetic energy.

So how come more light is created, 1 photon is absorbed, 1 is produced. I don't mean to seem like a dumbass, just want to make sure i'm happy with how it works smile.gif

#6 ad absurdum

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Posted 24 April 2006 - 06:53 PM

QUOTE(jambo david @ Apr 24 2006, 06:53 PM) View Post

QUOTE(gsmushet1 @ Apr 24 2006, 06:49 PM) View Post

It is destroyed as all of it's energy is given to the electron in the form of kinetic energy.

So how come more light is created, 1 photon is absorbed, 1 is produced. I don't mean to seem like a dumbass, just want to make sure i'm happy with how it works smile.gif
I *think* you are getting confused between two different things here.

The first is the photoelectric effect. This is when you have your metal with its free electrons and you let photons of energy hf be incident on the surface of the metal. If the photons have energy greater than the threshold frequency, they are able to eject an electron (photoelectron seems to get thrown about in place of this, although I was not taught this word) from the surface of the material.

This is kind of like stimulated emission. Say you've got a laser and the atoms in it are excited (by electricty). When a photon of the right frequency collides with this atom and knocks the electron down an energy level, thereby giving off another photon. In lasers (Light Amplification by Simulated Emission of Radiation) this is amplified - i.e. the original photon and the emitted photon are in phase and interfere constructively to create a wave of greater amplitude.
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#7 *Kiran*

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Posted 24 April 2006 - 07:58 PM

Thanks guys. This helped me alot also.
Much appreciated! biggrin.gif

#8 jambo david

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Posted 24 April 2006 - 08:31 PM

QUOTE(*Kiran* @ Apr 24 2006, 08:58 PM) View Post

Thanks guys. This helped me alot also.
Much appreciated! biggrin.gif

Yip, thanks. I really appreciate it

#9 dfx

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Posted 24 April 2006 - 09:24 PM

Wave particle duality is dodgy for beginners. I spose it's rather abstract to try to reconcile with classical physics. For anyone who reads the New Scientist or who can get hold of this week's copy, there's a really good cover story which features Young's Double Slit experiment.

#10 gsmushet1

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Posted 24 April 2006 - 09:31 PM

yeah...during photoelectric emission a photon is absorbed and an electron is ejected.....there is no ejection of light.

#11 gsmushet1

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Posted 25 April 2006 - 08:29 PM

you are getting it confused with stimluted emission which is when a electron falls from a high energy level to a lower one and hence the energy it loses is given off in the form of a photon.

#12 ice_illusion

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Posted 26 April 2006 - 11:03 PM

QUOTE(dfx @ Apr 24 2006, 10:24 PM) View Post

Wave particle duality is dodgy for beginners. I spose it's rather abstract to try to reconcile with classical physics. For anyone who reads the New Scientist or who can get hold of this week's copy, there's a really good cover story which features Young's Double Slit experiment.

Ooh thanks. I'll try and rescue it from my brother who keeps nabbing it.





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