Posted: Apr 12, 2017 2:48 pm
In electromagnetism, amplitude is defined as the difference between maximum and minimum values of the component electric and magnetic waves.
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Given Maxwell's four equations (which are based on observation) we have shown that electromagnetic waves must exist as a consequence. They can have any amplitude E0 (with B0 depending on E0 as will be shown later), any wavelength λ, and be retarded or advanced by any phase φ, but they can only travel through empty space at one wave speed c.
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