Complex amplitude of E-field and phase changes

In summary, the fresnel equations state that if the complex amplitude is positive, there is no phase change, but if it is negative, there is a phase change of π after reflection from the surface of an insulator. This is because a negative reflection coefficient means that the reflected E-field is opposite in direction to the incoming E-field, resulting in a phase change of π.
  • #1
km707
6
0
Hi,

I'm looking through my notes on em waves in dielectrics and the fresnel equations and I've been stuck on this for a while.

It states that if the complex amplitude = E0e is positive there is no phase change. However when the value is negative, the phase change Φ is π.. Why is that?

Thanks in advance!
 
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  • #2
It just means that after reflection from the surface of an insulator, then the reflection coefficient (the fraction between the incoming and reflected amplitude) might be either negative or positive. If positive, there is no phase change. If it is negative, then it means that the reflected E-field "points the other way" compared to the incoming E-field - which is just a π-change in phase (recall exp(iπ) = -1).
 

1. What is the complex amplitude of the electric field?

The complex amplitude of the electric field is a mathematical representation of the strength and direction of an electric field. It is a complex number that includes both the magnitude (amplitude) and phase of the field.

2. How is the complex amplitude of the electric field related to the amplitude and phase changes?

The complex amplitude of the electric field is directly related to the amplitude and phase changes of the field. Changes in the amplitude and phase can be represented by changes in the complex amplitude, which is also known as the complex electric field strength.

3. What is the significance of phase changes in the complex amplitude of the electric field?

Phase changes in the complex amplitude of the electric field represent changes in the direction of the electric field. This can affect the behavior of the electric field, such as interference patterns and polarization.

4. How is the complex amplitude of the electric field measured?

The complex amplitude of the electric field can be measured using various techniques, such as interferometry and polarimetry. These techniques involve measuring the amplitude and phase of the electric field at different points and using mathematical calculations to determine the complex amplitude.

5. Can the complex amplitude of the electric field change over time?

Yes, the complex amplitude of the electric field can change over time due to various factors such as changes in the source of the electric field, interactions with other fields, and propagation through different mediums. These changes can affect both the amplitude and phase of the field.

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