Electric field direction and permittivity

In summary, the direction of the electric field can be affected by the presence of a polarized material, causing a deviation in the force on a test charge placed nearby. This effect is possible and can be calculated using boundary conditions for electromagnetic fields and material constants. It is also possible for the force direction to change inside the material due to its influence. Further research is needed for more information on the calculation of this phenomenon.
  • #1
zrek
115
0
The electric field direction can be measured by the force affected on a test charge.

Let's put a point-like charge not far from a material, that is polarized by it.
See the figure:
permittivity1.png

The test force on the test charge A points exactly to the charge.

I think that because the surface is full of polarized particles in one direction, the test charge next to the surface (C) will behave differently, the force on it will points more perpendicular to the surface.

And also the inner test charges (like B) will be under the effect of the neighbour particles, so the direction of the force will point a little towards the surface.

Is this effect possible? Can the permittivity affect to the direction of the force?

Thank you for your toughts.
 
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  • #2
The test force on the test charge A points exactly to the charge.
There should be a slight deviation due to the material below it.
Is this effect possible? Can the permittivity affect to the direction of the force?
Yes it can.
 
  • #3
mfb said:
Yes it can.

Is it calculatable somehow? For example like the Snell's law?
 
  • #4
With the boundary conditions for electromagnetic fields - the parallel component of E and the perpendicular component of D are continuous, the field inside the material and outside are divergence-free, and D and E are proportional to each other* with some material constants.

For the surface, this should give something similar to Snell's law I think.

*there are materials where this is not true. It does not change the basic concept, however.
 
  • #5
mfb said:
... the field inside the material and outside are divergence-free...

Am I understand it well that inside the material the force on the test charge points (in avarage) exactly to the main point-charge?
 
  • #6
No, the direction there will be changed by the material, too.
 
  • #7
I googled the net, but I have not found relevant information about this. Please if anyone have a link about the calculation of how the force direction change inside the material, share this info, I'd be happy.
Thank you in advance!
 

1. What is an electric field and how is its direction determined?

An electric field is a physical field that surrounds an electrically charged object and exerts a force on other charged particles in its vicinity. The direction of the electric field is determined by the direction in which a positive test charge would move if placed in the field. This is known as the direction of the force on a positive test charge.

2. How does the permittivity of a material affect the strength of an electric field?

The permittivity of a material is a measure of its ability to store electric charge. In the presence of an electric field, a material with a higher permittivity will experience a larger displacement of its electric charge, resulting in a stronger electric field within the material.

3. What is the difference between electric field strength and electric field intensity?

Electric field strength refers to the force per unit charge experienced by a test charge in an electric field. On the other hand, electric field intensity is a measure of the strength of the electric field at a particular point in space, regardless of the presence of a test charge. It is determined by the electric field vector at that point.

4. How do you calculate the electric field direction and magnitude for a point charge?

The direction of the electric field for a point charge can be determined using the right-hand rule, where the thumb points in the direction of the electric field and the fingers point in the direction of the force on a positive test charge. The electric field magnitude can be calculated by dividing the force on a test charge by the magnitude of the test charge.

5. How does the shape and size of an object affect the electric field around it?

The shape and size of an object can affect the electric field around it in various ways. For example, a pointed object will have a higher electric field strength at its tip compared to a rounded object with the same charge. The distance from the object also plays a role, with the electric field becoming weaker as the distance increases.

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