What color is an electron?

Regardless of the answer to this question, I learned that electrons taste like grape-ade in “The Mathematics of Quantum Neutrino Fields”.

And what about the promised best answers? ;-)

Color is the subjective perception of visible light by an organism, not an intrinsic property of anything physical. Different organism see different colors depending on their photoreceptor wavelength response, and for the same reason it is possible to represent the same color with different spectrums.

Very cool image.

Presumably it is electrons changing energy states and giving off photons, whether they are in the electron beam or interacting with nitrogen ions.

Here's a picture of an electron beam outwards from the negative grid of my Fusor.  The vacuum was about 50 micron at the time.

So, are the electrons blue, or just the residual nitrogen ions lighting up as the electrons head to the positive grid?

Electrons seem to have a finite size, but it is much smaller than the wavelength of visible light, so in a wave model of light there may not be a reflection.

I don't know if it is a good analogy but if you have a water wave hitting a large solid wall, it will reflect off the wall. If you have a skinny pole sticking out of the water a large wave will not have a noticeable reflection off the pole. If the pole is wide enough, there will be a noticeable reflection.

A good explanation for my level of understanding, thank you. I think I got sidetracked into imagining the electron as a sphere with its own surface and that being illuminated. Maybe the electron doesn't have a surface/surface area in the same way other matter does?

[Apologies to physicists reading my comments.]

Photons of a specific energy are seen as a specific colour.

An electron that emits a photon will look like it is the colour of the photon at that instant, but it could be a different colour if the band gap that it jumps is different.

I don't think the photons emitted in a band jump are the characteristic colour of the electron, they are the characteristic colour of the bandgap energy.

Bandgap energies are a property of the material, not the electrons.

If you have a red and a green LED in series, it is the same electrons creating both photon colours, they are just jumping a different band gap in the different LED materials.

When you look at a lit LED, you are seeing the light (photons) emitted from electrons, so you could say that is their colour at that time.

Colour from reflected light is due to photons of most energies being absorbed and mostly just the colour seen being reflected.

Electrons can absorb photons of a lot of different energies which change their energy band, but I don't know if they can absorb just part of the energy of a photon and reflect or transmit part of it. Or if they can reflect all of it.

I understand what you've said there dougw but can't help mulling over your statement, which I know is also correct, so giving me a dilemma:

However electrons will emit a photon when jumping from a high energy band to a lower energy band.

Is the fact that the electron emits a photon (of a certain colour) the same as it actually having colour? When we state material has a colour is it not due to the reflection and absorption of light on its surface.

[ps: I like questions like this, it gets people thinking and discussing...]

The DeBroglie wavelength of a 1eV electron is about 1.23 nm.

The shortest visible wavelength is about 380 nm, so an electron would likely be invisible either from emitted light or from reflected light.

However electrons will emit a photon when jumping from a high energy band to a lower energy band.

The colour is dependent on how large a band gap they jump. (as clem57 indicated)