# How to proof the polarity of the reflected wave of Oblique incident.

1. May 30, 2013

### yungman

As shown in the attachment, the book assumes $\hat E_{||}^r=\hat y_r=(\hat x \cos \theta_r +\hat z \sin\theta_r)$. Why? How do you proof this. I have another post here about the Normal Incidence and no luck.

I am not even convinced that the reflected E is even in the Plane of Incidence, how do you even proof this. I have 5 EM books only Griffiths even attempt to proof in a way I don't even agree for the Normal Incidence. Every book pretty much just give the polarity. If anyone have article or notes, please share with me.

Thanks

Alan

#### Attached Files:

• ###### Oblique L.jpg
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2. May 30, 2013

### sudu.ghonge

Try solving the problem there. I faced the very same hurdle. The boundary conditions beautifully bring out the result

#### Attached Files:

• ###### griffiths.bmp
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3. May 30, 2013

### yungman

Actually this is exactly what I was struggling with in the other post:
For me, the proof I can accept is if $\hat n_R=\hat x \cos \theta_R+\hat y \sin\theta_R+ \hat z f(\theta_R)$ and proof that y and z component are both zero. Or better yet, proof reflection of a TEM wave is also a TEM wave.