Energy of Wave: Does Amplitude Affect E?

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Discussion Overview

The discussion revolves around the relationship between the amplitude of a wave and its energy, particularly in the context of different types of waves such as electromagnetic waves and sound waves. Participants explore the implications of Planck's equation and the concept of energy density in relation to amplitude and frequency.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asks if there is an equation that calculates the energy of a wave according to its amplitude and questions why amplitude does not affect energy in Planck's equation, which relates energy to frequency.
  • Another participant states that Planck's equation applies only to electromagnetic waves and notes that energy per wave is related solely to frequency, mentioning that the reason amplitude does not matter is complex.
  • A third participant references Einstein's work, explaining that light consists of photons and each photon's energy is dependent on its frequency, reiterating that the energy of one photon is given by h.f.
  • A later reply reiterates the initial question about amplitude and energy, suggesting that various formulas exist depending on the wave type and emphasizing that "energy of the wave" is not well defined. They introduce concepts like energy density and energy flux, which depend on both amplitude and frequency.
  • This participant also connects the quantum perspective, stating that Planck's formula gives the minimum energy of a photon, while total energy density or flux relates to the number of photons, which can be associated with classical amplitude.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between amplitude and energy, with some suggesting that amplitude does not affect energy in certain contexts while others propose that it does in terms of energy density and flux. The discussion remains unresolved regarding the overall impact of amplitude on energy across different wave types.

Contextual Notes

Participants highlight that the definition of "energy of the wave" varies and may depend on specific contexts such as standing waves or progressive waves. There are also unresolved aspects regarding the relationship between classical and quantum descriptions of wave energy.

jaumzaum
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Is there a equation that calculate the energy of a wave acccording to the amplitude

Another question, The plank equation E = h.f calculate the energy of any wave according to the frequency? If so, why doesn't the amplitude affect the energy (in the equation)?
 
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Plank's equation is only applicable to an Electromagnetic wave. IE Light. It was discovered that the energy per "wave" was only related to frequency of the light. As for WHY amplitude doesn't matter, that is complicated and beyond my knowledge.
 
Einstein's showed that (in his 1905 papers) light is made up of photons and each photon's energy depends on its frequency.
energy of 1 photon is h.f
 
jaumzaum said:
Is there a equation that calculate the energy of a wave acccording to the amplitude

Another question, The plank equation E = h.f calculate the energy of any wave according to the frequency? If so, why doesn't the amplitude affect the energy (in the equation)?

There are various formulas, depending on the type of the wave (EM, sound, etc). The "energy of the wave" is not a very well defined quantity. You may want to look at energy density, the energy in a specific unit volume, if it's a standing wave. Or maybe the energy flux, the energy transported by a progressive wave through a specific area in unit time.
In general these quantities depend on both the amplitude of the wave and frequency.

Now going to the quantum picture, the Plank formula gives the minimum energy (photon) that the wave may transport, exchange, etc. The total energy density or flux depends on the number of photons in the wave which can be related to the (classical) amplitude of the wave.
 

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