What is the Relationship Between Electromagnetic Amplitude and Power?

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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.