How Does a Hollow Conducting Sphere Affect Internal and External Charges?

In summary, the net electric force on the charges +q1 and +q2 will be zero as the positive charge at the center of the conducting sphere will induce equal and opposite charges on the inner and outer surface, causing a cancellation of the electric field and resulting in no net force on either charge. Therefore, none of the statements 1-5 accurately describe the net electric force on each charge.
  • #1
IWantToLearn
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A hollow, conducting sphere is initially uncharged. A positive charge, +q1, is placed inside the sphere (at the center). Then, a second positive charge, +q2, is placed near the sphere but outside it.

Which of the following statements describes the net electric force on each charge?
1-There is a net electric force on +q2 but not on +q1.
2-There is a net electric force on +q1 but not on +q2.
3-Both charges are acted on by a net electric force with the same magnitude and in the same direction.
4-Both charges are acted on by a net electric force with the same magnitude but in opposite directions.
5-There is no net electric force on either charge.



Attempt at a solution
I know that for a charged hollow spherical conductor, the charge is distributed on both the inner and outer surface of the conductor, and the net electric field in the material of the conductor is zero, also the net electric field inside the cavity is zero, and the net eelectric field in a point close to the outer surface is δ/ε0

but in this case there is a point charge at the center of the cavity, and the net electric field inside the cavity must has a nonzero value (due to the point charge).

i thought that both of the charges may cause the spherical conductor to be charged through induction, so the electric field due its charge inside the cavity is zero, and hence choice (1) will be relevant, but i am not sure.

i thought also that if the spherical conductor will remain uncharged, so there will not be a charge distribution in its surface, and the only remaining thing is the coulomb force between the two charges acting on each other, so choice (4) will be relevant.


please help
 
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  • #2
The charge at the center of the sphere will induce an equal and opposite charge on the inside of the conducting sphere and a equal and same charge on the outside of the sphere.

So what does that tell you?
 
  • #3
Liquidxlax said:
The charge at the center of the sphere will induce an equal and opposite charge on the inside of the conducting sphere and a equal and same charge on the outside of the sphere.

So what does that tell you?
if so, then the charge at the center will not be affected by the electric field of the induced charge distribution on the inner surface, cause the field inside the cavity is zero,
and the charge outside will be affected by the electric field of the induced charge distribution on the outer surface, if this is the case then choice (1) is the answer

But wait a minute, why not the charge outside the sphere induce a charge distribution on the the sphere similar way to the charge distribution induced by the inner charge
if this is true, then we will have a complex charge distribution, and i can't tell exactly about the force
 
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  • #4
the charge on the inside the sphere is positive so its field lines will be emitted radially outwards to the negatively charged sphere. There is a field inside the sphere from the positively charged particle

there will be zero force on the particle inside the sphere

Since a positive charge is induced on the outside of the sphere the charge outside the sphere will experience a force
 
  • #5
Liquidxlax said:
the charge on the inside the sphere is positive so its field lines will be emitted radially outwards to the negatively charged sphere. There is a field inside the sphere from the positively charged particle

there will be zero force on the particle inside the sphere

Since a positive charge is induced on the outside of the sphere the charge outside the sphere will experience a force

again why not the charge outside the sphere causes an induced electric charge distribution on the outer surface, so we have two overlapped charge distributions on the hollow sphere, one due to the inner charge and one due to the outer charge.

by the way the electric field at the center must be zero, and hence the force, so there is no force affecting the charge in the center.
 

FAQ: How Does a Hollow Conducting Sphere Affect Internal and External Charges?

What is a hollow conducting sphere?

A hollow conducting sphere is a scientific term used to describe a spherical shell made of a conducting material such as metal, with an empty space inside. It is often used as a model to study the behavior of electric fields and charges.

How does a hollow conducting sphere behave in an electric field?

A hollow conducting sphere has a unique behavior in an electric field. The electric field inside the sphere is always zero, regardless of the strength or direction of the external electric field. This is because the charges within the conducting material redistribute themselves in such a way that cancels out the external field inside the sphere.

What is the significance of a hollow conducting sphere in electromagnetism?

The hollow conducting sphere is an important concept in electromagnetism as it helps us understand the concept of electric shielding. It also serves as a useful model for calculating electric fields and potentials in more complex systems.

Can a hollow conducting sphere hold an electric charge?

Yes, a hollow conducting sphere can hold an electric charge. However, the charge resides only on the surface of the sphere and does not penetrate into the interior. This is due to the principle of electrostatic shielding.

How does the thickness of the hollow conducting sphere affect its behavior?

The thickness of the hollow conducting sphere does not affect its behavior in an electric field as long as the sphere is perfectly conducting. This means that the charge distribution and electric field inside the sphere remain the same regardless of its thickness. However, if the conducting material is not perfect, the behavior may change depending on the thickness of the sphere.

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