When does the phase change of \(\pi\) occur for EM wave reflections?

AI Thread Summary
The phase change of an electromagnetic wave upon reflection occurs when the wave transitions from a medium of lower to higher refractive index, resulting in a π phase shift. This phenomenon is observed in scenarios like Lloyd's mirror and non-reflective coatings on lenses. However, the phase change can also depend on factors such as the angle of incidence and the polarization of the wave, whether it is parallel or perpendicular to the surface. For waves with normal incidence, the phase change is straightforwardly linked to the refractive index transition. Understanding these conditions is essential for applications in optics and wave behavior.
h0dgey84bc
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Hi,

When exactly does the phase change of \pi occur when a EM wave reflects from a surface? I notice that it happens in Lloyd's mirror for example, and also when considering non reflective coatings on lenses. Is it just when the EM wave is going into a medium with higher refractive index or is there more to it than that?

Thanks
 
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h0dgey84bc said:
Is it just when the EM wave is going into a medium with higher refractive index or is there more to it than that?
For waves with normal incidence, that's all there is to it. But generally the phase change depends upon angle of incidence and polarization (whether the wave is polarized parallel or perpendicular to the surface).
 
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