Unable to excite n=2 electron in Bohr Model

[Nancy-Salpepi]

I'm currently not able to excite the electron in n=2 to a higher energy level in the Bohr model. It looks like a photon of the correct wavelength collides with the electron, but the electron doesn't move to a higher n value.

Discussed this with AR, CM and DT. CM will look into making the collision detection area larger.

hit.with.blue.photon.mp4

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For Bohr, the photon and electron collide if they intersect. See BohrModel collides.

Before I allow them to collide if they are "close enought", I'd like to understand why they are not colliding, and whether it's actually due to failure to collide.

So... notes to self. Things to verify, see BohrModel attemptAbsorption.

• Is the wavelength of the photon being recognized as absorbable?
• Is a collision occurring, or is the photon jumping over the electron in 1 timestep.
• Does absorption always occur? It looks like yes, since PHOTON_ABSORPTION_PROBABILITY = 1 in BohrModel.ts.

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@Nancy-Salpepi and I looked at this together.

What's happening in the movie above is that the electron has not been in it's state (n) for the minimum amount of time, so the collision with the blue (434 nm) photon is ignored. The minimium time that an electron must be in its current state is 1 sec (at Normal time setting), and that time is scaled for the Fast/Slow time settings (0.25 sec and 3 sec respectively). This same minimum time is used for all transitions, regardless of how they occur.

After experimenting a bit... Having a separate minimum time for photon absorption seems to resolve the problem, and 0.75 sec (at Normal time setting) seems to be a reasonable value. That is implemented in e4b9a50f6c983b0c2b611fad1e17d15541cc42cfm.

@Nancy-Salpepi please review. Close if OK.

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I said:

... The minimium time that an electron must be in its current state is 1 sec (at Normal time setting), and that time is scaled for the Fast/Slow time settings (0.25 sec and 3 sec respectively). ..

I discovered that this is not true -- they are not being scaled based on the Time Control setting, and they should be. So back to me to fix that.

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Hmmm... Now I'm wondering if we should scale these minimum times. They don't exist for any reason related to correctness of the model. They exist so that the electron state doesn't change so quickly that the student misses seeing something. In that case, perhaps the minimum time should not be scaled, and the same minimum used regardless of the Time Control speed setting.

On the other hand, if the electron was allowed to change state more frequently in the "Fast" setting, then emission would occur more frequently, and the spectrometer would built up faster.

@Nancy-Salpepi thoughts?

[Nancy-Salpepi]

I played with the sim this morning and I think it is fine as is. I am able to see what is happening with the electron/photons in slow speed and excite an electron from n=2. At fast speed it still takes under a minute to build up the spectrometer to see all the possible wavelengths and that some emissions are more common than others.