- #1

greypilgrim

- 547

- 38

I'm a bit puzzled that the classical formula for the intensity of a monochromatic, linear EM wave

$$I=\frac{1}{2}\cdot c\cdot \varepsilon_0\cdot E_0 ^2$$

seems to be independent of frequency whereas I find for the energy of a mechanical wave (e.g. on a string with total mass ##M##)

$$E=2\pi^2\cdot f^2\cdot A^2\cdot M\enspace .$$

Am I comparing apples and oranges or is it true that the energy transmitted per second per unit area only depends on the amplitude of the electric field?