# Does Recoiling Electrons Have 0 Energy When Photon is Scattered 180°?

• MostlyHarmless
In summary: In this case, if ##\theta = 180## degrees, the photon is scattered back in the direction of the incident photon.In summary, the energy of the "recoiling electrons" would be 0 and the change in wavelength is 0, indicating no scattering, if the angle of scattering is 180 degrees. This is consistent with the mathematical equation ##{\lambda}_2-{\lambda}_1={\frac{h}{m_ec}}(1-cos{\theta})## which shows that when ##\theta = 180##, the change in wavelength is 0. However, it is important to note that the scattering is still occurring, just in the opposite direction of the incident photon.
MostlyHarmless
I'm pretty sure this is a fairly obvious question, but I can't ever be sure..

So, if a photon is "scattered" 180 degrees. Its not being scattered at all, correct? So, then the energy of the "recoiling electrons" would be 0.

It makes sense mathematically if I'm doing it right.

##{\lambda}_2-{\lambda}_1={\frac{h}{m_ec}}(1-cos{\theta})##

##h## is Planck's constant, ##m_e## is electron mass, c, speed of light. If theta is 180, change is wavelength is 0, so then there is no scattering? Is the all consistent?

The reason I'm so hesitant, is because this is a homework problem, and the only one assigned dealing with recoiling electrons, so I figured it would be... less trivial.Note: Excuse the lack of homework template, I'm posting this off of my phone, which does not give me the template.

MostlyHarmless said:
So, if a photon is "scattered" 180 degrees. Its not being scattered at all, correct?

Not correct.

MostlyHarmless said:
So, then the energy of the "recoiling electrons" would be 0.

It makes sense mathematically if I'm doing it right.

##{\lambda}_2-{\lambda}_1={\frac{h}{m_ec}}(1-cos{\theta})##

##h## is Planck's constant, ##m_e## is electron mass, c, speed of light. If theta is 180, change is wavelength is 0, so then there is no scattering?

What is cos(180)?

>.< Doh. That's what I get for just punching it my calculator and then not writing it down.

hen it says, 180, its "scattering" back in the direction if the incident photon?

So the change in wave length should be ##2h/(m_ec)##?

Right. The angle ##\theta## is the angle by which the photon is deflected.

I would like to clarify that the concept of recoiling electrons and their energy in the context of photon scattering is not a trivial matter. It involves a complex interplay between the energy and momentum of the photon and the electrons involved in the scattering process.

Firstly, let's define what we mean by a "scattered" photon. In this case, we are referring to the process of Compton scattering, where a photon is absorbed by an electron and then re-emitted in a different direction. This process results in a change in the photon's energy and wavelength, as well as a change in the momentum of the recoiling electron.

Now, let's consider the scenario where the photon is scattered at an angle of 180 degrees. In this case, the change in the wavelength of the photon, as shown in the equation provided, is indeed 0. However, this does not mean that the photon is not scattered at all. It simply means that the photon is scattered back in the same direction from which it came, with no change in its energy or wavelength.

As for the recoiling electron, it does not have 0 energy in this scenario. While the change in its momentum may be 0, it still retains its initial energy before the scattering event. This is because the energy of the electron is not solely dependent on its momentum, but also on its mass and speed.

In conclusion, the concept of recoiling electrons and their energy in the context of photon scattering is not a trivial matter and requires a deeper understanding of the underlying principles of quantum mechanics. It is important to approach such problems with a critical mindset and to seek further clarification if needed.

## 1. What is the relationship between recoiling electrons and photon scattering at 180°?

The recoiling electrons are the result of a photon being scattered at 180°. This means that the photon has transferred its energy and momentum to the electrons, causing them to change direction and velocity.

## 2. Why is it important to study the energy of recoiling electrons during photon scattering?

Studying the energy of recoiling electrons during photon scattering can provide valuable insight into the properties of the photon and the interactions between particles. It can also help us understand fundamental principles of quantum mechanics and the behavior of matter.

## 3. Can recoiling electrons have 0 energy after being scattered by a photon at 180°?

No, recoiling electrons cannot have 0 energy after being scattered by a photon at 180°. This is because the energy and momentum of the photon must be conserved, meaning that the energy and momentum of the recoiling electrons must be non-zero.

## 4. How does the energy of the photon affect the energy of recoiling electrons in 180° scattering?

The energy of the photon directly affects the energy of the recoiling electrons in 180° scattering. The higher the energy of the photon, the higher the energy of the recoiling electrons will be.

## 5. Are there any other factors that can affect the energy of recoiling electrons in 180° photon scattering?

Yes, there are other factors that can affect the energy of recoiling electrons in 180° photon scattering. These include the angle of scattering, the properties of the material the electrons are scattering off of, and other particles that may be present in the interaction.

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