Point Charge in an uncharged spherical conductor

In summary, Gauss's Law can be used to determine the electric field in three different regions surrounding a point charge inside a hollow metal sphere. In region (i), where r is less than the inner radius of the sphere, the electric field is zero due to the conductor. In region (ii), between the inner and outer radii of the sphere, the electric field is also zero due to the conductor. In region (iii), where r is greater than the outer radius of the sphere, the electric field is the same as if the point charge were outside the conductor.
  • #1
SauerKrauter
7
0

Homework Statement



Consider a point charge q > 0 which is surrounded by a hollow metal sphere (uncharged) with inner radius R1 and outer radius R2. Use Gauss Law to determine the electric field E=E(r)er in the following regions:
(i) 0 < r < R1
(ii) R1 < r < R2
(iii) r > R2

Homework Equations



∫EdA = Q/ε

The Attempt at a Solution



(i) I believe the answer would be 0 because the electric field inside of an enclosed conductor is always zero
(ii) This is where my troubles really lie, don't know what to do here
(iii) I think that the electric field would be equatable to that of one where the point charge didn't exist outside the conductor as long as r is great enough, and i can solve for this
 
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  • #2
SauerKrauter said:

Homework Statement



Consider a point charge q > 0 which is surrounded by a hollow metal sphere (uncharged) with inner radius R1 and outer radius R2. Use Gauss Law to determine the electric field E=E(r)er in the following regions:
(i) 0 < r < R1
(ii) R1 < r < R2
(iii) r > R2

Homework Equations



∫EdA = Q/ε

The Attempt at a Solution



(i) I believe the answer would be 0 because the electric field inside of an enclosed conductor is always zero
(ii) This is where my troubles really lie, don't know what to do here
(iii) I think that the electric field would be equatable to that of one where the point charge didn't exist outside the conductor as long as r is great enough, and i can solve for this
What is the precise location of the charge in the hollow of the sphere?
Is it at the center of the hollow?
Is the center of the hollow coincident with the center of the sphere?​


For items (i) & (ii):
The electric field in the conducting material itself is zero. (This is useful for (ii) but not for (i). )
Nothing says that the electric field must be zero In the hollow of a conductor. Gauss's Law confirms this.​
 
  • #3
SauerKrauter said:

Homework Statement



Consider a point charge q > 0 which is surrounded by a hollow metal sphere (uncharged) with inner radius R1 and outer radius R2. Use Gauss Law to determine the electric field E=E(r)er in the following regions:
(i) 0 < r < R1
(ii) R1 < r < R2
(iii) r > R2

Homework Equations



∫EdA = Q/ε

The Attempt at a Solution



(i) I believe the answer would be 0 because the electric field inside of an enclosed conductor is always zero
Not if there is charge inside it!

(ii) This is where my troubles really lie, don't know what to do here
Can there be an E field in a conductor?

(iii) I think that the electric field would be equatable to that of one where the point charge didn't exist outside the conductor as long as r is great enough, and i can solve for this

I don't understand this statement.
 
  • #4
yes everything is concentric, and I'm starting to see my erroneous thoughts.

(i) would just be the field as if no conductor was present yes? because I am checking the field at which it hasn't reached the conductor

(ii) would be zero because it is inside of the conductor which means the net electric field is zero

(iii) i am now not sure on, but think that it may be the same answer as (i) because the charge (lets say positive) in the conductor would pull all the electrons to the inside, leaving the outside of the conductor positively charged just like it would be before. Is this correct in theory?
 
  • #5
SauerKrauter said:
yes everything is concentric, and I'm starting to see my erroneous thoughts.

(i) would just be the field as if no conductor was present yes? because I am checking the field at which it hasn't reached the conductor

(ii) would be zero because it is inside of the conductor which means the net electric field is zero

(iii) i am now not sure on, but think that it may be the same answer as (i) because the charge (lets say positive) in the conductor would pull all the electrons to the inside, leaving the outside of the conductor positively charged just like it would be before. Is this correct in theory?
Pretty much correct.

In (iii), it's not true that all the electrons are pulled to the inside. Gauss's Law tells us that just enough electrons are pulled to the inside so that the flux in the conducting material is zero. ...
 

What is a point charge?

A point charge is an idealized concept in physics that represents a particle with a single positive or negative charge, with no physical size or shape. It is often used to simplify calculations in electrostatics.

What is an uncharged spherical conductor?

An uncharged spherical conductor is a material that has no net electric charge and has a spherical shape. It can be made of various materials, such as metal or semiconductor, and is often used in electrical circuits and devices.

How does a point charge behave inside an uncharged spherical conductor?

A point charge inside an uncharged spherical conductor will experience a force in the opposite direction of its electric field lines. This is known as the Faraday cage effect, where the conductor shields the interior from external electric fields.

What is the electric potential inside an uncharged spherical conductor?

Inside an uncharged spherical conductor, the electric potential is constant and equal to the potential at its surface. This is because the electric field inside the conductor is zero, and the potential is directly related to the electric field by the equation V = -∫E•dl.

How does the electric field change at the surface of an uncharged spherical conductor?

At the surface of an uncharged spherical conductor, the electric field is perpendicular to the surface and has a magnitude that varies with the inverse of the distance from the center of the sphere. This means that the electric field is strongest at the edges of the surface and weakest at the center.

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