Charge on conducting and non-conducting body

In summary, charges on a body can be distributed throughout the entire volume only if the body is non-conducting, while the charge on a conducting body can only reside on the surface. This is because electric fields do not exist within conducting bodies, as any excess charges would move to cancel them out. In contrast, in non-conducting bodies, charges are bound to the atoms and can only move over a limited distance, resulting in polarization within the body. This restriction of movement allows for the distribution of charges throughout the entire volume.
  • #1
the charge on a body can be distributed throughout the entire volume only if the body is non-conducting,and the charge on a conducting body can reside only on the surface. I'm confused , why?
 
Physics news on Phys.org
  • #2
All charges are surrounded by lines of force (electric fields). If there are charges iwithin conducting bodies, there are also electric fields. But electric fields don't exist in conducting bodies, because if there were, the charges would move (conduct) to cancel the electric fields. Therefore there are no free (excess) charges within conducting bodies. There can be charges on the inside surface of a conducting sphere, but only if there are matching free charges within the enclosed volume. Gauss's theorem in the conducting sphere (integral[E*n da] = integral [rho dv] = 0) requires no electric field within the conducting sphere, so no net enclosed charge. In short, use Gauss's Law.
 
Last edited:
  • #3
Bob S said:
All charges are surrounded by lines of force (electric fields). If there are charges iwithin conducting bodies, there are also electric fields. But electric fields don't exist in conducting bodies, because if there were, the charges would move (conduct) to cancel the electric fields. Therefore there are no free (excess) charges within conducting bodies. There can be charges on the inside surface of a conducting sphere, but only if there are matching free charges within the enclosed volume. Gauss's theorem in the conducting sphere (integral[E*n da] = integral [rho dv] = 0) requires no electric field within the conducting sphere, so no net enclosed charge. In short, use Gauss's Law.

thanks... i got it ... but why can the charge be distributed throughout the entire volume only for a nonconducting body??/
 
  • #4
Because the charges are generally thought of as being bound to the atoms/molecule that make up the bulk material. Certain things can happen, but only over a limited distance. For example, in a non-conducting dielectric, the field does not strip the electrons and moves them about like it can in a conductor, but rather it stretches the atom into a dipole moment. The electrons bunch in the direction of the electric field leaving the nucleus to move away. This results in a small dipole moment. Since the bulk's dipole moments will follow the field, you get polarization within the dielectric.

The charge gets distributed throughout by the fact that it is restricted from moving about the bulk, unlike in a conductor.
 
  • #5
well ...yeah ..that makes sense...thanks.
 

Q1: What is the difference between a conducting and non-conducting body in terms of charge?

A conducting body allows charges to move freely throughout the material, while a non-conducting body does not. This means that charges can accumulate on the surface of a non-conducting body, but they cannot move through the material itself.

Q2: How does charge behave on a conducting body?

On a conducting body, charge will distribute itself evenly across the surface. This is known as the "Faraday cage effect," where the charges repel each other and spread out as much as possible.

Q3: Why does charge not distribute evenly on a non-conducting body?

Non-conducting bodies do not allow for the movement of charges, so the charges will accumulate on the surface and will not distribute evenly. This is why static cling can occur on non-conducting materials like plastic or rubber.

Q4: Can a non-conducting body hold a charge?

Yes, a non-conducting body can hold a charge. This is because the charges are unable to move through the material, so they remain on the surface. However, the charge may dissipate over time due to factors such as humidity and temperature.

Q5: How does the charge on a conducting body affect its surroundings?

The charge on a conducting body can affect its surroundings through electrostatic induction. This is when the charge on the body causes a separation of charges in nearby conducting materials, resulting in an attractive or repulsive force between the two surfaces.

Suggested for: Charge on conducting and non-conducting body

Back
Top