Why Electric Fields are perpendicular

[KatieD]

Homework Statement

If electric fields are perpendicular to the equipotential surface, what is the orientation of the field on the surface of a conductor (like metal)? Why is this so?

Homework Equations

E= ∆V/d

The Attempt at a Solution

I know that there is no charge within a conductor and it moves to the edges. I am confused with how this affects the electric field lines. I also know that electric field lines point out if a charge is positive and in if a charge is negative.

I am just confused with electric fields when there is a conductor.

Thanks :)
Katie

 

[berkeman]

Homework Statement

If electric fields are perpendicular to the equipotential surface, what is the orientation of the field on the surface of a conductor (like metal)? Why is this so?

Homework Equations

E= ∆V/d

The Attempt at a Solution

I know that there is no charge within a conductor and it moves to the edges. I am confused with how this affects the electric field lines. I also know that electric field lines point out if a charge is positive and in if a charge is negative.

I am just confused with electric fields when there is a conductor.

Thanks :)
Katie

If you use a DVM to measure the voltage difference between two points on a conductive surface, what voltage do you think you will measure (assuming little or no current is flowing in the conductor)? Does that help?

 

[KatieD]

You won't measure any voltage, does this mean that the electrical field would be zero?

 

[berkeman]

You won't measure any voltage, does this mean that the electrical field would be zero?

Something like that. It means that the two points on the conductive surface have no "potential" difference between them. So in other words, you could call the surface of a conductor an __________ surface, right? And since the E field is always perpendicular to that kind of surface, what can you say?

 

[KatieD]

Oh an equipotential surface! so the electric field would be perpendicular to the surface!

 

[KatieD]

(sorry it took me so long I had to leave for physical therapy)

 

[berkeman]

Oh an equipotential surface! so the electric field would be perpendicular to the surface!

Bingo!