What is the Relationship Between Electromagnetic Amplitude and Power?

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Discussion Overview

The discussion revolves around the relationship between electromagnetic amplitude and power, specifically how amplitude can be determined in relation to various parameters such as joules, length, and frequency. The scope includes conceptual understanding and technical explanation of electromagnetic waves.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions how to determine the amplitude of electromagnetic waves, seeking clarification on its relationship with joules, length, and frequency.
  • Another participant asks for clarification on whether the inquiry pertains to measuring amplitude or calculating it from other known values.
  • A third participant states that the square of the amplitude of the electric field is proportional to the irradiance (intensity) of the wave, which is measured in watts per square meter.
  • A later reply suggests that measuring power or irradiance can allow one to infer amplitude, provided certain assumptions about the wave's characteristics are met.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and approaches to the question, indicating that there is no consensus on the best method to determine amplitude or the specifics of its relationship with power.

Contextual Notes

The discussion includes assumptions about the nature of the wave, such as being monochromatic and infinite, which may not be universally applicable.

shintashi
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Hi, I have a question about electromagnetic amplitudes. we can easily find the wavelength of any EM, but how do we determine its amplitude? in terms of joules vs. length vs. frequency?
 
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I don't understand your question. How do you measure amplitude? or how do you calculate it given something else?
 
The square of the amplitude [of the electric field carried by the wave] is proportional to the irradience (intensity) of the wave, which is the power per unit area and hence has SI units of watts per square meter (W.m-2)
 
The easiest way is to measure the power or irradiance and infer the amplitude from there, assuming of course that the wave is monochromatic, infinite etc. etc.

Claude.
 

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