What's the meaning of amplitude in EM wave?

AI Thread Summary
Amplitude in electromagnetic (EM) waves refers to the magnitude of the electric field vector, which is crucial for defining the wave's polarization. Unlike water waves, where amplitude indicates the variation in water molecules, EM wave amplitude reflects the strength of the electric and magnetic fields. The square of the amplitude correlates with energy density, indicating that higher amplitude means more energy. However, the concept of amplitude in EM waves does not have an independent meaning outside of its relationship to the electric field. Understanding amplitude is essential for grasping the properties and behaviors of EM waves.
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i learned that EM wave is varying electric field and magnetic field .But what's the meaning of the amplitude of EM wave? The displacement of the photon or the magnitude of the electric/magnetic field(no. of photons)?
 
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Classically, the square of the amplitude of a wave is proportional to the energy [density].
 


but it doesn't have its own meaning?
in water wave, the amplitude is the magnitude of the variation of water molecular.
then what's varying in the EM wave?
 
particle said:
but it doesn't have its own meaning?
in water wave, the amplitude is the magnitude of the variation of water molecular.
then what's varying in the EM wave?

In the simplest form, it's the amplitude of the E-field vector. This is what typically defines the polarization of an EM wave.

Zz.
 

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