Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Not really a homework question per se, but i am just curious about this:

Energy of a wave is given by the planck relation, which should be proportional to its frequency.

However in electrical engineering we always learn that the energy of a wave is the square of its magnitude; nothing to do with frequency.

So are these 2 concepts equivalent?

Thanks.

share|improve this question
2  
Duplicate –  Vijay Murthy May 13 '12 at 9:33
add comment

2 Answers 2

The energy of a photon is $h\nu$, but that's the energy of an individual photon, not of the whole wave. The wave coming from, for example, your laser is made up from multiple photons and if you add up all the energies of the individual photons you'll get the total energy of the wave.

share|improve this answer
add comment

Good topic, energy of the wave does not depend on frequency only if you consider single bump of the wave, then YES its only about amplitude, otherwise total energy of the wave packet has to depend on the frequency (number of bumps per time). So in quantum physics you can think of the wave amplitude as being FIXED, then everything has to depend on the frequency of the wave packet -- we need energy per time.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.