Electric field of a coaxial cable

In summary, the conversation discusses the calculation of the electric field, electric potential, and enclosed charge in a coaxial cable with inner radius a and outer radius b. The cable is modeled as two long circular metal cylinders and a voltage is applied between them. The problem can be set up using cylindrical coordinates and Gauss's law due to the cylindrical symmetry of the system. The voltage can be taken into account by considering it as the potential difference between the two cylinders.
  • #1
balanto
5
0
We have a coaxial cable with inner radius a and outer radius b. The coaxial cable is modeled as two very long circular metal cylinders. I'm supposed to calculate the electric field E, the electric potential V and the charge enclosed Q when a voltage is applied between the metal cylinder, meaning between the inner conductor and the outer conductor

I know that if I can calculate the electric field the electric potential 'V and Q should not be hard to find. But how do i set up the problem? Is there any symmetry that allows me to use gauss law or am i stuck with using superposition?
If the case is that we have symmetry(which is a hard thing for me to figure out?) then we can use cylindrical coordinates and set up the problem as the integral of E dot ds and E=Er*r^ (because the electric field is pointing radially?) and ds=r^rdzd(theta)
But i have a hard time understanding the voltage that is applied, how do I take that into account when it comes to the integral above? Maybe I'm thinking totally wrong
 
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  • #2
Hi! :)
I would not like to say anything wrong, but I think the following:
Because the cable consist of two metal cylinders, I think we have a cylindrical symmetry.
It should be possible to find an expression for the electrical field (with dependence on r) from Gauss's law.
Then, one should remember that the integral of E along a distance (the difference in radius between the two cylinders) is the potentialdifference, which is the same as voltage.
 

1. How is the electric field of a coaxial cable calculated?

The electric field of a coaxial cable can be calculated using the equation E = V/d, where E is the electric field strength, V is the voltage applied to the cable, and d is the distance between the inner and outer conductors of the cable.

2. What is the direction of the electric field in a coaxial cable?

The electric field in a coaxial cable is radial, meaning it points outward from the center of the cable towards the outer conductor.

3. How does the diameter of a coaxial cable affect the electric field?

The diameter of a coaxial cable affects the electric field by changing the distance between the inner and outer conductors. As the diameter increases, the electric field decreases, and vice versa.

4. Can the electric field of a coaxial cable be shielded?

Yes, the electric field of a coaxial cable can be shielded by using materials such as metal or foil around the outer conductor, which helps to reduce interference and signal loss.

5. How does the presence of dielectric material affect the electric field in a coaxial cable?

The presence of dielectric material, such as plastic or rubber, between the inner and outer conductors of a coaxial cable can increase the electric field strength due to its insulating properties. This can lead to a more efficient transmission of electrical signals.

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