Why does long wavelength mean more energy OR less energy

  • #1

Main Question or Discussion Point

When looking at say water waves, long wavelength means high energy e.g. a tsunami, and waves in a rough sea - compared say to ripples on a pond. But when looking at photons and electrons and other "matter waves", short wavelength equals high energy. Why is it completely the opposite?
 

Answers and Replies

  • #2
mathman
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The comparison is somewhat off base. Tsunami energy is primarily a matter of amplitude (a ten foot wave has a lot more energy than a six inch wave), not wavelength. In the case of photons, we are comparing individual photons, i.e. one photon of a short wavelength (high frequency) has more energy than a longer wavelength photon.
 
  • #3
jambaugh
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As mathman said. For quantum particles the issue is energy per quantum which is higher for higher wavelength quanta. Water waves are very different animals.

One aspect of water waves is that they are "non-linear". You can't just pile two waves of the same wavelength on top of each other and get one wave twice as strong but with the same wavelength. Increasing the energy of the wave means involving larger volumes of water.

Things are doubly different for Tsunami waves. Regular daily wind driven waves are surface waves while Tsunami waves involve motion of water all the way down to the sea floor. This makes them behave even more non-linearly in some ways.
 

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