What is the force exerted on an electron if it absorbs a photon with frequency v

In summary, the photon exerts a force on the electron because it has a higher energy than the electron.
  • #1
az2212
10
0
if an electron was moving with velocity V1 then it absorbed a photon with frequency v to move with velocity V2 thus, what is the force exerted on that electron ? what is the formula that describes the force as a function of frequency?
 
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  • #2
az2212 said:
if an electron was moving with velocity V1 then it absorbed a photon with frequency v to move with velocity V2 thus, what is the force exerted on that electron ? what is the formula that describes the force as a function of frequency?
You would have to know the time that it took for the photon to be absorbed. [itex]\Delta p = F\Delta t[/itex].

I am not sure how an electron can absorb a photon by itself. But let's assume that it can.

Assume the electron is a point charge. It would completely absorb the photon in the time it takes for the photon to pass it (keep in mind that the photon is always traveling at speed c relative to the electron, regardless of the electron's speed). So, how big is the photon? And how long does it take the photon to pass a point in space?

AM
 
  • #3
is the a physical formula describes the force as a function of frequecy

Is there a physical formula describes the force as a function of frequency
HOW can we describe the force as a function of frequency?
 
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  • #4
az2212 said:
Is there a physical formula describes the force as a function of frequency
HOW can we describe the force as a function of frequency?

What branch of Physics are you dealing with? If you give more details about the specific question, then you are more likely to receive an answer.
 
  • #5
I mean the quantized force. for example, if an electron absorbed a photon with frequency v, then its velocity will change, thus what the force exerted on this elecron. I want a formula describe that, gives a force as a function of frequency.
 
  • #6
how can we compute the time required to the electron to absorb this photon? since according heiseberg uncertainty principle it impossible measuring the energy and time as the same time. where the photon is an energy.
 
  • #7
I wonder how one would set up the Schrödinger's equation for the interaction between an electron and a photon...
 
  • #8
tim_lou said:
I wonder how one would set up the Schrödinger's equation for the interaction between an electron and a photon...

You just write down the Hamiltonian so that it includes the electromagnetic interaction.

Andrew: A free electron can not absorb a photon. An electron bound to an atom or a band electron in a solid for example can. Even then the electron does not absorb the photon but the whole atom or solid does.
 
  • #9
how the photon can not absorb the photon ...in the photoelectric the electron absorb a photon with frequency v to move in a kinetic energy E where E=hv-hv0
 
  • #10
az2212 said:
how the photon can not absorb the photon ...in the photoelectric the electron absorb a photon with frequency v to move in a kinetic energy E where E=hv-hv0

You need to study things more carefully than this.

In a photoelectric effect, the METAL (or the cathode material) is the one that absorbs the photon. The presence of the lattice ions is necessary not only for the energy BANDS that allow for such a transition, but also to absorb and provide the RECOIL momentum. A free electron sitting there cannot do this, and that's why you do not get a "photoelectric effect" from a bunch of free electron gas.

Zz.
 
  • #11
thank you very much Mr ZapperZ
But how can we describe the fore as a function of frequency?
or there is no formula and there is no force in quantum
 
  • #12
az2212 said:
thank you very much Mr ZapperZ
But how can we describe the fore as a function of frequency?
or there is no formula and there is no force in quantum

As people here have mentioned, your question is undefined!

A "force" is a generic term for ANY action. You can't just ask something like that and expect to have a useful answer. What force are you referring to? If we are talking about the force that causes an apple to fall, then there is no "frequency".

Secondly, the term "force" is really quite secondary once you get into more complicated system. It appears that you have never encounter the Lagrangian/Hamiltonian mechanics, something that all physics majors in college have to go through and understand. Here, there is no "force" that is necessary to describe completely the dynamics of a system. This concept is carried through into quantum mechanics. That is why when we try to solve the description of a system, we write down the Hamiltonian/Schrodinger Equation. We do not deal with "force".

So if you're trying to connect "force" with the energy carried by light that has a connection to frequency, then this is a rather dubious way of trying to understand something. That is why you are not getting any answer to your question.

Zz.
 
  • #13
ZapperZ said:
As people here have mentioned, your question is undefined!

A "force" is a generic term for ANY action. You can't just ask something like that and expect to have a useful answer. What force are you referring to? If we are talking about the force that causes an apple to fall, then there is no "frequency".

Secondly, the term "force" is really quite secondary once you get into more complicated system. It appears that you have never encounter the Lagrangian/Hamiltonian mechanics, something that all physics majors in college have to go through and understand. Here, there is no "force" that is necessary to describe completely the dynamics of a system. This concept is carried through into quantum mechanics. That is why when we try to solve the description of a system, we write down the Hamiltonian/Schrodinger Equation. We do not deal with "force".

So if you're trying to connect "force" with the energy carried by light that has a connection to frequency, then this is a rather dubious way of trying to understand something. That is why you are not getting any answer to your question.

Zz.
Dear Zapperz
Thank you very much for your answer... I really trying to connect the energy carried by light that has connection to frequency. in fact i reached to a formula as: F=Hv/V,, whereas F is force, H is constant and equals to 6.6*10^-34 joule. like the value of plank's constant but defferent in dimension, and v is the frequency, and V is the velocity equivalent to the energy frequency. This formula gives us the relativistic quantized force and it can be applied for micro and macro. i hope to send me your openion.
 
  • #14
az2212 said:
Dear Zapperz
Thank you very much for your answer... I really trying to connect the energy carried by light that has connection to frequency. in fact i reached to a formula as: F=Hv/V,, whereas F is force, H is constant and equals to 6.6*10^-34 joule. like the value of plank's constant but defferent in dimension, and v is the frequency, and V is the velocity equivalent to the energy frequency. This formula gives us the relativistic quantized force and it can be applied for micro and macro. i hope to send me your openion.

My opinion here is that (i) you haven't learn much physics yet and (ii) you obviously missed the "overly speculative" rule in our Guidelines, even when you were warned about it earlier.

Zz.
 

1. What is the relationship between frequency and force in the absorption of a photon by an electron?

The force exerted on an electron when it absorbs a photon is directly proportional to the frequency of the photon. This means that as the frequency of the photon increases, the force exerted on the electron also increases.

2. How does the energy of a photon affect the force exerted on an electron?

The energy of a photon is directly related to its frequency, so the higher the energy of the photon, the higher the force exerted on the electron. This is because higher energy photons have a shorter wavelength, leading to a stronger interaction with the electron.

3. What determines the direction of the force on the electron when it absorbs a photon?

The direction of the force on the electron is determined by the direction of the photon's electric field. If the electric field of the photon is perpendicular to the electron's motion, the force will be in the same direction as the electron's motion. If the electric field is parallel to the electron's motion, the force will be in the opposite direction.

4. Can the force exerted on an electron by a photon be measured?

Yes, the force exerted on an electron by a photon can be measured using techniques such as atomic force microscopy or laser tweezer experiments. These techniques can detect tiny changes in the position or motion of the electron, allowing for the measurement of the force.

5. Is the force exerted on an electron by a photon constant?

No, the force exerted on an electron by a photon is not constant. It is dependent on the properties of the photon, such as its energy and direction of travel, as well as the properties of the electron, such as its charge and motion. Additionally, the force can change over time as the electron interacts with other particles or fields.

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