Energy of Photon  [ENDORSED]

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Ryan Neis 2L
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Energy of Photon

Postby Ryan Neis 2L » Wed Oct 18, 2017 12:17 am

I know that the energy of a photon has to be greater than the energy to remove an electron in order for light to be absorbed, but what happens when the energies are equal to each other? Is there a difference in outcome or in the values of the velocity of the electron?

David Minasyan 1C
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Re: Energy of Photon  [ENDORSED]

Postby David Minasyan 1C » Wed Oct 18, 2017 12:25 am

From what I know (and if someone would confirm) if the energy of the photon equals the amount of energy to eject the electron then that electron is ejected with a 0 kinetic energy.

Michelle Dong 1F
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Re: Energy of Photon

Postby Michelle Dong 1F » Wed Oct 18, 2017 9:14 am

The kinetic energy is the "excess energy," so there would be no excess energy to remove the electron from the metal.

Elika Asis 3C
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Re: Energy of Photon

Postby Elika Asis 3C » Wed Oct 18, 2017 10:56 am

Since the equation for kinetic energy is E(photon) - E(energy required to remove e-) = E(excess) = Ek, if the energy of the photon would cancel out the threshold energy/work function and it would lead the kinetic energy to equalling zero. So, the electron would be emitted with Ek = 0!
Hopefully that helps a little bit

Madelyn Gehrich 1E
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Re: Energy of Photon

Postby Madelyn Gehrich 1E » Wed Oct 18, 2017 1:38 pm

This would mean that the kinetic energy is equal to 0. Kinetic energy is something that is considered excess in the energy equation involving the photon, and if the kinetic energy is equal to 0 then that would be the maximum wavelength of that photon as well.

aaron tang 2K
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Re: Energy of Photon

Postby aaron tang 2K » Fri Oct 20, 2017 12:05 am

When the energy is equal to each other, the energy is still enough to emit a photon, but the kinetic energy would be zero.

Sarah Brauer
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Re: Energy of Photon

Postby Sarah Brauer » Fri Oct 20, 2017 1:33 am

Would light be emitted with zero kinetic energy?

Ramya Lakkaraju 1B
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Re: Energy of Photon

Postby Ramya Lakkaraju 1B » Fri Oct 20, 2017 2:39 am

Yes, if the energy of the photon exactly matches the work function of the metal, the electron that is emitted will have zero kinetic energy.

Jean Mok 3K
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Re: Energy of Photon

Postby Jean Mok 3K » Fri Oct 20, 2017 2:44 am

If the energy of the photon is exactly equal to threshold energy, or "the energy [required] to remove an electron" as you put it, then the electron is ejected. However, because all of the energy was consumed as work, there is no more energy to translate into kinetic energy, thus the velocity of the ejected electron would be zero. I hope this answered your question!

Michelle Lu 1F
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Re: Energy of Photon

Postby Michelle Lu 1F » Sun Oct 22, 2017 4:14 pm

I know that the energy of a photon has to be greater than the energy to remove an electron in order for light to be absorbed, but what happens when the energies are equal to each other? Is there a difference in outcome or in the values of the velocity of the electron?

Yes, when the energy of the incoming photon is greater than the threshold energy (defined as the energy to remove an electron from that surface), then the difference between these two energy values is the kinetic energy of the electron released. Thus, when the energies are equal, this merely means that the kinetic energy of the ejected electron is 0 J.


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