# 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!