Kinetic energy and e = hv


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rkang00
Posts: 21
Joined: Thu Sep 27, 2018 11:25 pm

Kinetic energy and e = hv

Postby rkang00 » Sun Oct 14, 2018 11:39 pm

If an electron is ejected with zero kinetic energy, what would it look like in real life? How would the electron actually move? Also, if kinetic energy is zero I guess this means that the work function (threshold energy) and hv are equal to each other?

Haowen_Liang_3E
Posts: 15
Joined: Fri Apr 06, 2018 10:03 am

Re: Kinetic energy and e = hv

Postby Haowen_Liang_3E » Mon Oct 15, 2018 9:35 am

I would think if Ek is 0, then the electron is not ejected. For the experiment, they had a slightly positive surface that will attract the electron with a small amount of Ek.

Albert Duong 1B
Posts: 25
Joined: Thu Sep 27, 2018 11:17 pm
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Re: Kinetic energy and e = hv

Postby Albert Duong 1B » Mon Oct 15, 2018 12:29 pm

The concept is quite similar to escape velocity, the lowest velocity an object needs to escape gravity. The electron will barely escape the surface of the material with no leftover energy. It will continue to move; however, its speed will keep decreasing as it gets further and further, but will never quite come to a complete stop (velocity approaches 0).

MaggieMatern_Dis1H
Posts: 22
Joined: Thu Sep 27, 2018 11:19 pm

Re: Kinetic energy and e = hv

Postby MaggieMatern_Dis1H » Tue Oct 16, 2018 8:52 pm

You are correct in assuming that if the kinetic energy is zero, that means that the work function is equal to (E=hv), as the energy of the photon was the exact amount needed for the particular threshold. Therefore, the electron is released but has no 'leftover' energy for kinetic energy, so it has no velocity.


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