E=0 inside the conducting sphere Always?

In summary: However, in most practical situations, E=0 is a good approximation inside a metallic/conducting sphere.
  • #1
gracy
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An uncharged metal sphere suspended by a silk thread is placed in a uniform external electric field E.(a)What is the magnitude of the electric field of points inside the sphere?(b)Is your answer changed if the sphere carries a charge?
I would have asked this in homework forum but it does not involve any calculations and I have also been provided with it's answer ,I am just going to ask a conceptual question based on the answer

Answer:(a)##E##=0
(b)
No
As we can see there is silk thread then there is external field to confuse the student that there is a special kind o set up hence there can be ##E##≠0 inside the metallic/conducting sphere but the answer is as usual ##E##=0 So it Does it mean ##E##=0 inside the metallic/conducting sphere no matter what.
Or are there any examples any set up any situation where ##E##≠0 inside the metallic/conducting sphere
 
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  • #2
For the most part, it does not matter. The metal sphere shields the interior from external electromagnetic forces - acting as a Faraday cage.

There are extreme cases. If you suddenly deposit a charge onto one spot on the sphere, that charge will move across the surface of the sphere at almost the speed of light. During that short time, the interior of the sphere will be exposed to a non-uniform electric field.

If a voltage can be maintained across the surface of the metal sphere, a charge could be induced. It the "metal" is not superconducting, this could be done by putting a current through the ball and counting on the resistance to create the voltage.

Also, a voltage can be induced with a strong magnetic field.

But, for normal situation and for common purposes, the charge will remain uniform.
 
  • #3
gracy said:
Does it mean EE=0 inside the metallic/conducting sphere no matter what.
Or are there any examples any set up any situation where EE≠0 inside the metallic/conducting sphere
E=0 is guaranteed inside a conductor only in the electrostatic case. In cases where there are currents or changing fields then there may be E fields inside a conductor.
 
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1. What does "E=0 inside the conducting sphere" mean?

"E=0 inside the conducting sphere" means that the electric field inside a conducting sphere is zero. This is because in a conducting material, the free electrons can easily move and redistribute themselves in response to an external electric field, canceling out any electric field inside the material.

2. Is the electric field really zero inside a conducting sphere?

Yes, the electric field is truly zero inside a conducting sphere. This is a fundamental principle of electrostatics and can be mathematically proven using Gauss's law.

3. Why does the electric field become zero inside a conducting sphere?

The electric field becomes zero inside a conducting sphere because of the redistribution of free electrons in the material. As the electric field exerts a force on these electrons, they move in such a way that the net electric field inside the material becomes zero.

4. Does this mean that there is no charge inside a conducting sphere?

No, there can still be charge inside a conducting sphere. However, the distribution of this charge will be such that the net electric field inside the material is zero.

5. What are the practical implications of "E=0 inside the conducting sphere"?

The most significant practical implication of "E=0 inside the conducting sphere" is that any electrically charged objects placed inside the sphere will experience no net force due to the electric field. This is why conductors are often used to shield sensitive equipment from external electric fields.

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