What is the validity of the relation $c = \nu\lambda$? More specifically, is this equation valid only for Electromagnetic waves?
I read this statement in a book, which says:
de Broglie waves are not electromagnetic in nature, because they do not arise out of accelerated charged particle.
This seems correct, but arises a doubt in my mind.
Suppose I find out the wavelength of a matter wave (or de Broglie wave) using de Broglie's wave equation: $$\lambda = \frac{h}{p}$$
Now, can I use $c = \nu\lambda$ to find out the frequency of the wave?