### E=hv

Posted:

**Thu Oct 25, 2018 2:20 pm**In the equation, E=hv, does E represent the energy of the photon or does it represent the energy required to remove an electron?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=15&t=34804

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Posted: **Thu Oct 25, 2018 2:20 pm**

In the equation, E=hv, does E represent the energy of the photon or does it represent the energy required to remove an electron?

Posted: **Thu Oct 25, 2018 2:24 pm**

The value E represents the energy of the photon. However, you can use the equation E=hv to calculate the energy required to remove an electron after taking into account the kinetic energy. This works because the energy of the photon must be greater than or equal to the energy required to remove the electron.

Posted: **Thu Oct 25, 2018 2:45 pm**

E=hv represents the energy of the photon. However, it could also be equal to the energy required to remove an electron if the kinetic energy is 0. This is shown in the formula E(photon) - work function = Kinetic energy. If the Kinetic energy is 0, then the energy of the photon is equal to the work function.

Posted: **Thu Oct 25, 2018 6:06 pm**

When it says we should be able to calculate the number of photons from this equation, we must have the total energy before we can do that, right?

Posted: **Thu Oct 25, 2018 6:27 pm**

E represents the energy of the photon but you can also use this equation to find the energy needed to remove the electron, just remember to pay attention to kinetic energy.

Posted: **Fri Oct 26, 2018 5:15 pm**

The work function is the energy needed to remove an electron.

Posted: **Fri Oct 26, 2018 11:56 pm**

E represents the energy of the photon, while the work function is the minimum energy needed to remove an electron.

Posted: **Sat Oct 27, 2018 10:54 am**

E is the energy of the photon. That equation is used to find the energy of a photon of light going at a certain speed. H is Planck's constant and v is the frequency of the electron. If E is equal to or greater than the threshold energy required to release an electron from an atom, then the electron is released.

Posted: **Sat Oct 27, 2018 12:47 pm**

E in this case is E(photon). The work function is the energy required to eject an electron in a 1:1 photon:electron interaction.

Posted: **Sat Oct 27, 2018 6:56 pm**

The E in E = hv represents the energy of a photon. The E in Ek = 1/2(mv^2) represents the excess energy after an electron is removed from a metal.

Posted: **Mon Oct 29, 2018 1:10 pm**

I understand that...

...but, can someone please clarify what the specific values are that we need to assign as hv and 1/2(mv^2)? Sorry if this was already stated!

Keshav Bhatnagar wrote:The E in E = hv represents the energy of a photon. The E in Ek = 1/2(mv^2) represents the excess energy after an electron is removed from a metal.

...but, can someone please clarify what the specific values are that we need to assign as hv and 1/2(mv^2)? Sorry if this was already stated!

Posted: **Mon Oct 29, 2018 4:03 pm**

Here, E would represent the energy of the photon

Posted: **Mon Oct 29, 2018 4:28 pm**

The E would represent the energy of the photon. The work function or threshold energy would be the energy required to remove an electron.

Posted: **Mon Oct 29, 2018 5:09 pm**

E represents the energy of the photon. h is Plancks's Constant (6.63*10^-34) and v is the calculated or measured frequency of a light source (typically UV or above for these equations)

Posted: **Thu Dec 06, 2018 6:31 pm**

Chase Yonamine 1K wrote:In the equation, E=hv, does E represent the energy of the photon or does it represent the energy required to remove an electron?

e represents the energy of a photon. The works function represents the energy required to remove an electron.

Posted: **Fri Jun 28, 2019 9:25 pm**

I know that E represents the energy of the photon, while the equation itself represents electron removal... In lecture today Professor Lavelle showed us an example of the electron removal from a metal. My question is can electrons be removed anywhere?

Posted: **Fri Jun 28, 2019 10:03 pm**

The professor only mentioned metals when talking about the photoelectric effect. Can it happen to other materials as well?

Posted: **Sat Jun 29, 2019 2:20 pm**

I don't think electrons can be removed from anymore I think there is more like a specific way in which it can be removed only. Maybe when it is jumping off the metal only?

Posted: **Sat Jul 06, 2019 4:54 pm**

E in E=hv represents the energy of a photon.

Posted: **Sat Jul 06, 2019 6:15 pm**

Represents the energy of the photon meanwhile the work function is the amount of energy needed to remove it.

Posted: **Sat Jul 06, 2019 8:25 pm**

E is the energy of the photon. The work function, on the other hand, would give you the energy needed to remove an electron.

Posted: **Thu Oct 10, 2019 3:11 pm**

It represents the energy of a photon, but can be used to find energy needed.

Posted: **Thu Oct 10, 2019 3:49 pm**

E represents the energy of a photon, and change in E can be used to find the difference in energy levels

Posted: **Thu Oct 10, 2019 10:57 pm**

Keshav Bhatnagar 1H wrote:The E in E = hv represents the energy of a photon. The E in Ek = 1/2(mv^2) represents the excess energy after an electron is removed from a metal.

Just to clarify, if there is excess energy after the electron is ejected, that energy would be converted to kinetic energy (Ek). The v in the equation Ek=1/2(mv^2) refers to the velocity of the electron, correct? Because surely it is not referring to nu, as in E=hv.

Posted: **Fri Oct 11, 2019 12:03 am**

Nicholas_Gladkov_3H wrote:Just to clarify, if there is excess energy after the electron is ejected, that energy would be converted to kinetic energy (Ek). The v in the equation Ek=1/2(mv^2) refers to the velocity of the electron, correct? Because surely it is not referring to nu, as in E=hv.

Correct, the v refers to the velocity of the electron and not nu. This is because kinetic energy deals with objects in motion, so having v represent the velocity of a moving object makes sense in this context. Hope this helps clarify the difference!

Posted: **Fri Oct 11, 2019 12:08 am**

E=energy of photon

h=planck's constant (6.626 × 10-34 m^2*kg/s)

v=frequency in Hz

h=planck's constant (6.626 × 10-34 m^2*kg/s)

v=frequency in Hz

Posted: **Fri Oct 11, 2019 1:16 am**

E in this equation represents the energy of the photon. In some cases, it could also be equal to the energy required to remove an electron if the kinetic energy is 0. This is shown in the formula E(photon) - work function = Kinetic energy. If the Kinetic energy is 0, then the energy of the photon is equal to the work function.

Posted: **Fri Oct 11, 2019 5:47 am**

E represents the energy of a photon, however it also can be used to find energy that is needed.

Posted: **Sun Oct 13, 2019 7:58 pm**

E in the equation represents energy but can also be used to find the energy needed to remove an electron!

Posted: **Sun Oct 13, 2019 10:56 pm**

haleyervin7 wrote:When it says we should be able to calculate the number of photons from this equation, we must have the total energy before we can do that, right?

yes, it needs to b e calculated from the work function and kinetic energy values given

Posted: **Mon Oct 14, 2019 8:37 pm**

E is supposed to represent the energy of a photon

Posted: **Mon Oct 14, 2019 9:17 pm**

E=hv is to find the energy of a photon(light) and is usually coupled with the c=lambdaxvelocity because c represents the speed of light. When combined these two equations create the E=hc/lambda equation. If you want to find the energy contained in an electron, you would use the De Broglie equation as it is a different form of energy.

Posted: **Mon Oct 14, 2019 9:22 pm**

E represents the energy (in joules) of the particle of light.

Posted: **Tue Oct 15, 2019 6:08 pm**

The E represents the amount of energy of a photon but you can always compare that E value to the work function value to determine whether the E amount is enough to remove the electron from one shell to another.

Posted: **Tue Oct 15, 2019 8:05 pm**

E represents the energy of the photon while work represents the amount of energy it takes to remove the electron from the metal

Posted: **Tue Oct 15, 2019 10:11 pm**

E=hv is the incoming energy of electromagnetic radiation (photon). The energy needed to remove electron is the work function (represented by a greek alphabet).

Posted: **Wed Oct 16, 2019 3:33 pm**

E represents the energy of the photon.

Posted: **Sat Oct 19, 2019 9:42 pm**

With this particle equation, E represents the energy of the photon.

Posted: **Sat Oct 19, 2019 10:13 pm**

E represents the energy of the photon. The energy required to remove an electron is known as the work function/threshold energy and is not present in this equation.

Posted: **Sun Oct 20, 2019 2:07 pm**

E represents the energy of the photon, as it is the constant times the wavelength.