Energy formula?

Question

According to google, Energy = Amplitude^2, then would two waves with different frequencies with the same amplitude have the same energy? Please show me an equation where both amplitude and frequency are added in to find a frequency, or tell me that frequency doesn't matter and the energy is the same. Thanks (sources! I love them!)

Answer 1

You mean intensity or maybe power, but not not 'energy'.



For example, in classical electromagntism the average intensity (average energy transferred per second per square metre) of an electromagnetic wave only depends on the amplitudes of the electric and magnetic fields. The frequency is irrelevant.



Look up Poynting vector for more info' - but it can get quite mathmtical.



(It gets more complicated in quantum mechanics though because we have to think in terms of photons rather than waves.)

Answer 2

Now. It should read as the proportional to amplitude square.

x- a sin w t

dx/dt = a w cos wt

Square it and take average.. The kinetic energy = 1/2 mass*a^2*w^2.

Therefore, the energy is propotional to the amplitude square but there is a multiplier w^2( frequency^2).

Answer 3

Oh, you're talking about the energy a wave! That's E = hf, Energy = Planck's constant times frequency.



But what you're asking? An amplitude and frequency to find a frequency? That doesn't make sense. But I think this is what you're talking about with amplitude and energy.