Question

2. if one visible red wave is 700 nm in length, and one visible violet wave is 400 nm in length How many possible colors can there be?

Answer 1

Between the value 400 nm and 700 nm there is an infinite amount of real values that can represent the length of a wavelength.

If we consider that each differente wavelength represents a different color, therefore there are infinite possible colors in the interval from 400 nm to 700 nm.

But if we consider only certain intervals of wavelength as certain colors, we can have for example 7 colors:

Violet, Indigo, Blue, Green, Yellow, Orange, Red.