# Does an electric field go through a conductor ?

• jaredvert
In summary: If we measure the field exactly on the inner surface of the shell we'll find it's zero (because the +q inside is cancelling it out there) but the moment we move either into the hollow interior or outside the shell, the shell's +q adds to the +q at the center and we get a field corresponding to +2q.In summary, the electric field in a conductor is not zero, but it is only present on the outer surface of the conductor. Inside the conductor, the field is cancelled out by the movement of negative charges to the inner surface of the conductor. This can be seen by measuring the field between the inner and outer surfaces of the conductor, which will come out to be zero. Additionally, if
jaredvert
I know there is no net flux in a conductor but do they go through the conductor? Say you have a positive q charge inside a hollow sphere that's charged pos q as well. Well that charge from the inner shell should keep penetrating space until it hits a negative charge which implies it goes through the conductor meaning the electric field in a conductor isn't zero. Just that the same number in go out as well. Am I correct? Thanks

jaredvert said:
I know there is no net flux in a conductor but do they go through the conductor? Say you have a positive q charge inside a hollow sphere that's charged pos q as well. Well that charge from the inner shell should keep penetrating space until it hits a negative charge which implies it goes through the conductor meaning the electric field in a conductor isn't zero. Just that the same number in go out as well. Am I correct?

No. What happens is that the negative charges in the conductor are attracted by the electrical field of the positive charge in the center, so they move to the inside surface of the shell (it's a conductor, so they can move around freely within it). That leaves the outside surface of the shell with a net positive charge.

We end up with the positive charge in the center generating an electric field throughout the interior of the shell; this field is stopped cold at the inner surface of the shell where negative charges have piled up to cancel it; then no field at all between the inner and outer surfaces of the shell; then the positive charge on the outer surface of the shell filling the entire universe outside the shell with an electrical field.

The only way you could tell the difference between what actually happens (field stops at the inner surface of the shell and starts up again at the outer surface) and what you describe (field passes through the conductive shell, same out as in) is by measuring the field between the inner and outer surfaces of the shell.. This has been done, and it comes out zero.

I understood the original question differently.
What if we have a +q charge inside the shell, but the shell on its own also has a +q charge?
Would the inside charge also attract electrons leaving the outside of the shell still more positive?
Then there would still be no field inside the conductor but outside we would measure a +2q charge, right?

danjordan said:
I understood the original question differently.
What if we have a +q charge inside the shell, but the shell on its own also has a +q charge?
Would the inside charge also attract electrons leaving the outside of the shell still more positive?
Then there would still be no field inside the conductor but outside we would measure a +2q charge, right?

Right. And in the hollow interior of the shell we'd just see the field from the single +q in the center.

I can confirm that an electric field does indeed go through a conductor. However, it is important to note that the electric field inside a conductor is not uniform and can vary depending on the distribution of charges within the conductor. In the scenario you described, with a positive charge inside a hollow sphere that is also positively charged, the electric field will indeed penetrate the conductor until it reaches a negative charge. This is because the charges within the conductor will redistribute in response to the external electric field, causing the electric field to pass through the conductor. However, it is also important to note that the net flux of the electric field through the conductor is still zero, as the same number of field lines will enter and exit the conductor. This is due to the fact that conductors have free electrons that can move in response to an external electric field, creating an equal and opposite electric field that cancels out the external field within the conductor. Therefore, while the electric field does go through the conductor, the net effect is still zero. I hope this helps clarify your understanding.

## 1. How does an electric field interact with a conductor?

When an electric field is applied to a conductor, the electric charges within the conductor will redistribute themselves. This redistribution of charges creates an electric field within the conductor that is equal in magnitude but opposite in direction to the external electric field. This results in a cancellation of the external electric field within the conductor, making the electric field effectively zero inside the conductor.

## 2. Can an electric field pass through a conductor?

No, an electric field cannot pass through a conductor. As mentioned before, the redistribution of charges within the conductor effectively cancels out the external electric field, preventing it from penetrating the conductor.

## 3. Why is it important for an electric field to not pass through a conductor?

It is important for an electric field to not pass through a conductor because if it did, it would create a flow of electric current within the conductor. This can potentially damage the conductor and any connected devices. By preventing the electric field from passing through, the conductor is able to safely carry electric charges without experiencing any disruptions.

## 4. What happens to an electric field when it reaches the end of a conductor?

When an electric field reaches the end of a conductor, it will either be reflected or transmitted. This depends on the properties of the conductor, such as its shape and material. In some cases, the electric field may also be partially absorbed by the conductor.

## 5. Can a conductor completely block an electric field?

No, a conductor cannot completely block an electric field. As mentioned before, the electric field will either be reflected, transmitted, or partially absorbed when it reaches the end of the conductor. However, by properly designing the conductor and its surroundings, the amount of electric field that is allowed to pass through can be minimized.

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