Electric field at the surface of a conductor

In summary, the electric field at the surface of a conductor cannot have a parallel component in a static situation because it would cause the charges on the surface to move, violating the condition of rest. However, this same statement is not valid for an insulator because the charges in an insulator are not mobile and the presence of a parallel component of the electric field would not cause them to move. Therefore, the statement does not hold for insulators in a static situation.
  • #1
jakeham
1
0

Homework Statement


Put in plain words: "In a static situation, the electric field at the surface of a conductor can have no component parallel to the surface, because this would violate the condition that the charges on the surface are at rest."
Would this same statement be a valid one for tha electric field at the surface of an insulator?


Homework Equations


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The Attempt at a Solution


I can't understand the sentence, and can't figure out if it's valid for an insulator.
 
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  • #2
The charges in a conductor are mobile. If there is a parallel component of the electric field at the surface then it will cause the surface charges to move (hence not 'static'). The charges in an insulator are not mobile. So the argument doesn't hold.
 
  • #3
In a STATIC situation, the charges ARE at rest. The statement holds
 
  • #4
chaoseverlasting said:
In a STATIC situation, the charges ARE at rest. The statement holds

The 'statement' is that there is no E field component parallel to the surface of the body. In the insulating case the charges won't move even if there is an E field. Hence there CAN be a E field in the static case. Hence the statement does NOT hold.
 

FAQ: Electric field at the surface of a conductor

What is an electric field at the surface of a conductor?

The electric field at the surface of a conductor is the force per unit charge experienced by an electric charge placed on the surface of the conductor. It is a vector quantity and is measured in units of volts per meter.

How is the electric field at the surface of a conductor calculated?

The electric field at the surface of a conductor can be calculated using the equation E = σ/ε, where E is the electric field, σ is the surface charge density, and ε is the permittivity of the material the conductor is made of.

Is the electric field at the surface of a conductor always perpendicular to the surface?

Yes, the electric field at the surface of a conductor is always perpendicular to the surface. This is because any tangential component of the electric field would cause charges to move along the surface, which would result in a non-equilibrium state.

How does the shape of a conductor affect the electric field at its surface?

The shape of a conductor does not affect the magnitude of the electric field at its surface, as long as the surface charge density remains constant. However, the direction of the electric field may vary depending on the shape of the conductor.

Can the electric field at the surface of a conductor be manipulated?

Yes, the electric field at the surface of a conductor can be manipulated by changing the surface charge density through the addition or removal of charges, or by changing the permittivity of the material the conductor is made of. This can be done using external sources such as batteries or by changing the surrounding environment.

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