What is the frequency of radiation that has a wavelength of 0.952 µm?

Frequency domain vs. Wavelength domain? Why is wavelength domain preferred?

• When I observe teaching methods about light, the electromagnetic spectrum, and black body radiation, I consistently see statement 1 below a lot more than I see statement 2 below. This occurs with any definition of "color" or region of the EM spectrum. Statement 1: the wavelength of red light is 750 nanometers Statement 2: the frequency of red light is 400 Terahertz Yes, both of them are true, but I feel that statement 2 is a better definition of red. This is because when that red light travels through diamond, its wavelength is 310 nm instead of 750 nm as it is in a vacuum. However, this particular shade of red will always have the frequency of 400 THz, no matter how optically dense the medium is. So, why is wavelength domain consistently preferred in teaching, even though wavelength changes with the refractive index of the medium?

• Answer:

  Wavelength is generally used becase it makes the maths simpler. When using a wave equation there are two variables, time and space. It is then easy to keep time constant and look at the wave over a distance, because our function is in terms of distance and time. Wavelength has units of meters (or similar) and we can therefore create an expression fairly easily. It is possible to do the same with frequency (and sometimes it can be easier in certain applications) but when doing more complex tasks like applying calculus or modeling certain conditions like boundries and changes in refractive index. As far as I know this is why it is more common to be taught using wavelength rather than frequency, even for simple stuff.