Photons and electron, a gap in my learning.

[zonniboy]

I’m not sure if this is the right forum for my question so this was my best guess since it deals with photons. I’ve only gone through my first few physics classes that explain the classic structure of the atom, electromagnetic spectrum and the likes. I’ve also read a few books on physics on my own. But I seem to find a gap in my learning when it comes to photons interacting with electrons.

I’ve learned that a photon can exite an electron and send it to the next energy state if such photon has the right amount of energy. But nothing is metioned , either in class or in any book that I have read, on what happens if such photon hits an electron but doesn’t have enough energy to move it to the next state. What really happens with that package of energy? If it’s not enough to move an electron from one state to the other then does it just get wasted and dissappear or does it bounce off the electron or what?

 

[mathman]

You can't think of photon-electron interaction like billiard ball collisions. If the photon energy is too little, it just passes by (nothing happens).

 

[R0man]

First of all, it's great that you are actively seeking to fill in any gaps in your learning! As for your question, it's a common one and it's important to understand the full picture of what happens when a photon interacts with an electron.

When a photon hits an electron, there are a few possible outcomes depending on the energy of the photon and the energy state of the electron. If the photon has enough energy to excite the electron to a higher energy state, then the electron will absorb the photon and move to the next energy level. This is what you have learned in your classes.

However, if the photon does not have enough energy to excite the electron, then there are a few different possibilities. One possibility is that the photon will simply pass by the electron without any interaction. Another possibility is that the photon will be absorbed by the electron, but instead of moving to a higher energy state, the electron will just gain a small amount of energy and remain in its current state. This is known as elastic scattering.

In some cases, the photon may also be absorbed by the electron and then immediately re-emitted, known as inelastic scattering. This can happen when the energy of the photon is close to the energy needed to excite the electron, but not quite enough. In this case, the photon transfers some of its energy to the electron, causing it to vibrate or move slightly, and then the electron releases the excess energy as a new photon.

So to answer your question, when a photon hits an electron but doesn't have enough energy to move it to the next state, the energy is not wasted or disappeared. It may be absorbed and then re-emitted as a new photon, or it may have no interaction at all with the electron. It's important to keep in mind that the behavior of photons and electrons can be complex and can vary depending on the specific conditions of the interaction.

I hope this helps to fill in the gap in your learning and gives you a better understanding of how photons and electrons interact. Keep asking questions and seeking out new knowledge, it will only enhance your understanding of physics!