Polarization of EM Waves: Understanding Its Role in Electrodynamics

In summary, polarization is a way of describing the orientation of the electric field vector component of an electromagnetic wave. The electric and magnetic fields are always normal to each other and their direction is related to the direction a test charge would travel from the force induced by the fields. The convention is to use the electric field as the direction of reference for polarization. Both the electric and magnetic fields can generate polarization in an electromagnetic wave, but it is convention to use the electric field as the cause of polarization.
  • #1
astro2cosmos
71
0
i read this "in electrodynamics, polarization characterizes em waves, such as light, by specifying the direction of the wave's electric field" in a book.
i really didn't get it clear & does the magnetic filed nothing to do with polarization?
 
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  • #2
The electric and magnetic fields are always normal to each other for an electromagnetic wave. In a source-free homogeneous region of space, the electromagnetic waves can only be transverse waves. This means that the electric and magnetic field vectors are both normal to the direction of propagation. So, if we specify the vector direction of the electric field and propagation, then we have implicitly specified the direction of the magnetic field. By convention, we generally choose the electric field as the direction of reference for polarization.

Electric and magnetic fields are both vector fields. Not only do they have a magnitude and phase associated with each point in space, but they also have a direction. This direction is related to the direction that a test charge would travel from the force induced by the fields. For example, the Lorentz force on a test charge due to the electric field is simply
[tex]\mathbf{F} = q\mathbf{E}[/tex]
So that is why there is a direction associated with the fields (the relationship with the magnetic field is a bit more complicated, the cross product of the particle's velocity and magnetic field).

So the polarization of the electromagnetic wave is a way of describing the orientation of the electric field vector component of the wave as the wave propagates through space and time.
 
  • #3
Born2bwire said:
The electric and magnetic fields are always normal to each other for an electromagnetic wave. In a source-free homogeneous region of space, the electromagnetic waves can only be transverse waves. This means that the electric and magnetic field vectors are both normal to the direction of propagation. So, if we specify the vector direction of the electric field and propagation, then we have implicitly specified the direction of the magnetic field. By convention, we generally choose the electric field as the direction of reference for polarization.

Electric and magnetic fields are both vector fields. Not only do they have a magnitude and phase associated with each point in space, but they also have a direction. This direction is related to the direction that a test charge would travel from the force induced by the fields. For example, the Lorentz force on a test charge due to the electric field is simply
[tex]\mathbf{F} = q\mathbf{E}[/tex]
So that is why there is a direction associated with the fields (the relationship with the magnetic field is a bit more complicated, the cross product of the particle's velocity and magnetic field).

So the polarization of the electromagnetic wave is a way of describing the orientation of the electric field vector component of the wave as the wave propagates through space and time.
how the polarization will affect by change in the direction of electric field?
 
  • #4
astro2cosmos said:
how the polarization will affect by change in the direction of electric field?
What do you mean? The polarization is the direction of the electric field.
 
  • #5
astro2cosmos said:
i read this "in electrodynamics, polarization characterizes em waves, such as light, by specifying the direction of the wave's electric field" in a book.
i really didn't get it clear & does the magnetic filed nothing to do with polarization?

The magnitude of the electric field is roughly 'c' times larger than the magnitude of the magnetic field; that is why the electric field is used.
 
  • #6
In an EM wave the E and B fields are always at right angles to each other, so when you specify the direction of one, it automatically determines the direction of the other. We could use either one as the "polarization direction", but by convention we use the E field, to be consistent.
 
  • #7
jtbell said:
In an EM wave the E and B fields are always at right angles to each other, so when you specify the direction of one, it automatically determines the direction of the other. We could use either one as the "polarization direction", but by convention we use the E field, to be consistent.

is there any polarization is generated by magnetic field ? likewise electric field.
& why polarization is only cause of eletric field?
 
  • #8
astro2cosmos said:
is there any polarization is generated by magnetic field ? likewise electric field.
Yes, if the wave is polarized then both the magnetic and electric fields are polarized.

& why polarization is only cause of eletric field?
As jtbell said, it is by convention. By widespread agreement, the electric field is used to specify the polarization direction. If you are told what that direction is, then you know the direction of both the electric and magnetic fields.
 

What is polarization of EM waves?

Polarization of EM waves refers to the direction in which the electric field oscillates as the wave travels through space. This direction can be linear, circular, or elliptical.

Why is polarization important in electrodynamics?

Polarization plays a crucial role in understanding the behavior of electromagnetic waves in various materials and environments. It affects how the waves interact with matter, as well as their transmission, reflection, and absorption properties.

How is polarization of EM waves determined?

The polarization of an EM wave is determined by the orientation of the electric field vector relative to the direction of wave propagation. This can be measured using polarized filters or by analyzing the wave's interference pattern.

What are the different types of polarization?

The three main types of polarization are linear, circular, and elliptical. Linear polarization occurs when the electric field oscillates in a single plane, while circular polarization occurs when the electric field rotates in a circular manner. Elliptical polarization is a combination of both linear and circular polarization.

Can the polarization of EM waves be changed?

Yes, the polarization of EM waves can be changed by passing them through a polarizing filter or by reflecting or refracting them at certain angles. They can also be converted from one type of polarization to another through various optical devices.

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