# B Color and Wavelengths

1. May 18, 2017

I have read that color of light percieved by us depend on its wavelength since light is wave and also electron has wave like character that means electron has wavelength .Does that mean that electron has a color associated with it . I think its not but why .also I'm not able to understand why does color of light depend on its wavelength

2. May 18, 2017

### vanhees71

Color is not a physical but a physiological concept, and you cannot simply map color to a frequency in a one-to-one way.

Electrons have quantum character as any matter in the universe but no wave-like properties. In non-relativistic Quantum mechanics a single electron can be described by a complex valued field, obeying the Schrödinger equation (or better Pauli equation if you include spin as you should for the electron), which has wave-like solutions.

However it's not a classical field like, e.g., the electromagnetic field, either. The modulus squared of the wave function rather gives the probability distribution to find the electron at a given place when looking for it at a given time: $P(t,\vec{x})=|\psi(t,\vec{x})|^2$ (here I left out the spin-degree of freedom for simplicity).

3. May 18, 2017

### nasu

Sound is also a wave. An elastic wave. Elastic waves induced in solids by thermal motions may have wavelengths all the way down to a few angstroms. Some will be in the range of wavelengths for visible light. However you cannot see them and there is no sensation of color produced by these waves.
Actually even the medical ultrasound nowadays reaches into GHz so the wavelength in water (or tissue) will be in the range of hundreds of nano-meters, same as for visible light. But again, you don't see the colors if they use it to scan the eye.

So the point is that the wavelength is not all it matters. Each receptor (eye included) is sensitive to a specific type of wave.