B Higher frequency => higher energy

1. May 29, 2016

LLT71

can someone explain why high frequency waves contain higher energy?

thanks!

2. May 29, 2016

Chandra Prayaga

If these are EM waves we are talking about, then each photon has energy equal to hf where h is Planck's constant and f is the frequency of the wave. To say that high frequency waves "contain" higher energy is not quite correct. The energy of a wave is proportional to the square of the amplitude, which is related to the number of photons. So certainly it is correct to say that a photon of higher frequency has higher energy.

3. May 29, 2016

Staff: Mentor

All else being the same, it takes a stronger restoring force to produce a higher frequency oscillation - the easiest way to see this is to play around with the equation for a simple harmonic oscillator. A stronger restoring force means more energy is needed to produce the same displacement.

Another intuitive answer: The energy of a wave is in whatever pushes the peaks up and the troughs down. A higher frequency means more peaks and troughs, hence more energy.

Both of these answers are imprecise and hand-wavy descriptions of something that is clear and precise in the math.

4. May 29, 2016

LLT71

thank you guys!