I'm curious as to how we know the wavelength of light. Correct me if I'm wrong, but my understanding of light is that it is travelling variations/vibrations in the electromagnetic field, as such it has a speed and a frequency, and therefore a wavelength...but since light isn't really a little squiggly line like many drawings depict it, then light can't truly have a wavelength in the way that most people think of it. So my question is: does light really have a wavelength, and if so, how does it manifest, what's the best way to conceptualize of it? Sure light waves aren't little moving lines of energy with the wavelength being the space between peaks, right? Oh yeah, and how do we know the wavelength of light for various frequencies? Is it just by measuring the frequency and speed and doing the math, or have we actually measured the wavelength directly? If so, how? Thank you so much!