EM Radiation Amplitude: Is Peak Related to Intensity?

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Discussion Overview

The discussion centers around the relationship between the peak amplitudes of electric and magnetic fields in electromagnetic radiation and their connection to the radiation's intensity. It explores theoretical aspects of electromagnetic radiation and its parameters.

Discussion Character

  • Technical explanation

Main Points Raised

  • One participant questions whether the peak amplitudes of electric and magnetic fields are related to the intensity of electromagnetic radiation.
  • Another participant provides a reference to the Poynting vector and discusses the relationship between intensity (Power Flux Density) and the RMS amplitudes of the electric and magnetic fields, noting that intensity is expressed in W/m².
  • The same participant explains that the Power Flux Density (PFD) can be calculated using the intrinsic impedance of the medium and provides formulas relating PFD to the electric and magnetic field amplitudes, indicating that using peak amplitudes will result in halving the PFD compared to using RMS amplitudes.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the relationship between peak amplitudes and intensity, as the initial question remains open and further exploration is indicated.

Contextual Notes

The discussion does not clarify the assumptions behind the use of peak versus RMS amplitudes or the implications of the intrinsic impedance in different media.

jeremyfiennes
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Electromagnetic radiation is propagating sinusoidal electric and magnetic fields. Are the peak amplitudes of these fields in any way related to the radiation's other parameters, e.g. its instensity?
 
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jeremyfiennes said:
Electromagnetic radiation is propagating sinusoidal electric and magnetic fields. Are the peak amplitudes of these fields in any way related to the radiation's other parameters, e.g. its instensity?
Intensity is Power Flux Density, expressed in W/m2. The RMS amplitudes of the electric and magnetic fields are related to PFD in the following way, where R is the intrinsic impedance of the medium, 377 Ohms for free space:-
PFD = E^2 /R
PFD = R H^2
R = E/H
If using peak amplitudes rather than RMS, the PFD will be halved.
 
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Thanks.
 
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