Energy Levels

[Will Pham 1J]

I was a bit confused from the lecture, because Dr. Lavelle said if the energy that is being transmitted to the electron does not exactly match the energy of the higher energy level(s), then the light would not be absorbed. However, a google search said "All the photons with energy equal or higher than the energy level difference will get absorbed.", so does that mean photons that do not exactly match the energy level, but are higher than said energy level will be absorbed?

[Anna Martin 2l]

I also had the same question as you and was a little confused about this. But, I believe that in the lecture, he talked about how the energy of the photon must be greater or equal to the energy needed to remove the electron. So, as long as it is at least equal to the energy, then it should be able to eject the electron. Hope this helps!

[Sondia Luong 1C]

Hi, I think what that google search means is that photons with energy higher than the energy level difference is referring to if the photon has enough energy to match the energy difference through multiple levels. Dr. Lavelle stated in his lecture that even if photons have excess energy, if it doesn't match the energy difference between energy levels, then it will not be absorded by the electron at all. If anything, it should be safe to go along with what the professor says instead of that google search because he has stressed this fact in his lectures and module videos!

[Sophia Kalanski 1A]

Hi! So I think what he meant in his lecture was that the energy of the photon has to be atleast equal to/match the energy needed to move the electron up an energy level. It just can't be less than the needed energy to eject it.

[Alex Benson]

Hi! This is something that I didn't fully understand as well. I believe that Lavelle is referring to the photon needed to meet a particular energy threshold before it becomes fully ejected.

[Vince Li 2A]

I feel like I have a general understanding of this. It is important to remember that everything is quantized. You either absorb the EXACT wavelength of light or you don't. There is no in between. As a result, if you absorb a frequency of light that is larger than what you want, supposing that the frequency of light does not meet a higher energy level, it will not be absorbed, because it is not that EXACT frequency of light. It doesn't matter if the frequency of light is higher, because the light containing that frequency is only that frequency.

[SashaAnand2J]

Hi Will!
From my understanding, photons that push electrons over the energy threshold will bounce off the metallic surface in the form of kinetic energy (refer to the work function). I'm also a little confused by your Google search, but I'm assuming that the light is absorbed while energy itself is deflected? It is also possible that the material in question is not a metallic surface, which is why the excess energy would be absorbed.

[Izamary Marquez 2H]

With regards to energy levels in the Balmer or Lyman series, is there a specific reason why the energy is negative. For example, E4=-1/16hR and E2=-1/4hR. Is this because the light is being emitted and energy is released?

[Ralph Zhang 2L]

I think what the professor meant is that any amount of energy that is in between the quantized values will not be emitted back as light when the electron go down in energy levels. The energy is there but is irrelevant to the experiment.