Hello everybody, I have a question about the Fresnel equations at normal incidence. My textbook gives the reflection coefficients as:(adsbygoogle = window.adsbygoogle || []).push({});

(1) perpendicular polarization

rs=( n1*cos(theta1)-n2*cos(theta2) ) / ( n1*cos(theta1)+n2*cos(theta2) )

(2) parallel polarization

rp=( n2*cos(theta1)-n1*cos(theta2) ) / ( n1*cos(theta1)+n2*cos(theta2) )

Now, to me, it seems that for normal incidence on a dielectric interface, the polarization loses its meaning since neither the E- or H-fields have components normal to the surface. Put another way, the plane of incidence has lost its meaning. In this case, shouldn't the 2 Fresnel equations for reflection give the same result? If you put 0 degrees in to those two equations they have opposite signs. What gives?

I'm probably spending too much time think about this, but any help making sense of this would be greatly appreciated!!

Thanks,

Brian

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# Fresnel equations at normal incidence

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