# Determine the polarity of the reflected EM wave.

• yungman
In summary, the polarity of the reflected wave is determined by \Gamma, which is dependent on the difference in intrinsic impedance between the two media. If this difference is negative, the reflected wave will have opposite polarity to the incident wave, as shown in the upper left drawing. If the difference is positive, the reflected wave will have the same polarity as the incident wave, as shown in the upper right drawing. For further understanding, please read the provided article.
yungman
Attached are the drawings. Does the polarity Eof depend on $\Gamma =\frac {\eta_2-\eta_1}{\eta_2+\eta_1}$

So if $\eta_2<\eta_1$, the Γ is negative and the polarity of the reflected wave is opposite polarity?

I understand $\theta_i=\theta_r$ and all that. As shown in the drawing, if you look at the TEM wave travel from the left at z=-ve, in medium 1, hitting the boundary on xy plane at z=0, say it is perpendicular polarization where $\vec {E}= \hat {y} E(z)$, which is parallel to the boundary. If $\eta 1 > \eta 2\;\Rightarrow\; \Gamma=-ve$, is $\vec {E}_r$ in opposite direction...$\vec {E}_r=-\hat {y} E_r$ as in the upper left drawing.

And if $\eta 2 > \eta 1\;\Rightarrow\; \Gamma = +ve$, then $\vec {E}_r=\hat{y}E_r$. This is shown in the upper right drawing.

The upper left shows $\eta 1 > \eta 2$ where Ei and Er are pointing in y direction. In drawing on top right where $\eta 1 < \eta 2$, Er is in -ve y direction.

I drew the case where Ei is on the xz plane as shown in lower left drawing, how do I even determine the direction of the reflection based on the intrinsic impedance of the two media? Please help. Please provide some article links if you can.

Thanks

Alan

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• Refraction.png
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Yes, the polarity of the reflected wave will depend on \Gamma. If \eta_2<\eta_1, then the Γ is negative and the polarity of the reflected wave will be opposite to the incident wave. This can be seen in the lower left drawing; the incident wave is traveling along the xz plane and the reflected wave will travel in the opposite direction (i.e., -ve x direction). For more information, please refer to this article: https://www.researchgate.net/public..._an_interface_between_two_uniform_dielectrics

## 1. How is the polarity of a reflected EM wave determined?

The polarity of a reflected EM wave is determined by analyzing the direction of the electric and magnetic fields of the wave. If the electric field and magnetic field are perpendicular to each other, the wave is considered to have a linear polarization. If the electric field rotates in a single plane, the wave is considered to have circular polarization.

## 2. Can the polarity of a reflected EM wave change?

Yes, the polarity of a reflected EM wave can change depending on the angle of incidence and the properties of the reflecting surface. When a wave is reflected at an angle, the electric and magnetic fields are also rotated, resulting in a change in polarity.

## 3. How does the polarity of a reflected EM wave affect its properties?

The polarity of a reflected EM wave can affect its properties such as its direction of propagation, intensity, and ability to be transmitted through certain materials. For example, waves with linear polarization can pass through polarizing filters, while circularly polarized waves cannot.

## 4. What is the difference between positive and negative polarity in a reflected EM wave?

The polarity of an EM wave refers to the direction of its electric and magnetic fields. In a positive polarity, the electric and magnetic fields point in the same direction, while in a negative polarity, they point in opposite directions. This can affect the behavior of the wave when interacting with other waves or materials.

## 5. How is the polarity of a reflected EM wave related to its wavelength?

The polarity of a reflected EM wave is not directly related to its wavelength. However, the wavelength of an EM wave can affect its polarity if it interacts with certain materials. For example, when a wave with a long wavelength is reflected off a surface, it may experience a change in polarity due to the properties of the surface.

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