Question

To understand the behavior ofthe electric field at the surface of a conductor, and itsrelationship to surface charge on the conductor.
A conductor is placed in an external electrostatic field. Theexternal field is uniform before the conductor is placed within it.The conductor is completely isolated from any source of current orcharge.

1.Which of the following describes the electricfield inside this conductor?

a.It is in thesame direction as the original external field.
b.It is in theopposite direction from that of the original externalfield.
c.It has adirection determined entirely by the charge on itssurface.
d.It is alwayszero.

2.The charge density inside theconductor is:

a.0
b.non-zero;but uniform
c.non-zero;non-uniform
d.infinite

3.Assume that at some point just outside thesurface of the conductor, the electric field has magnitudeE and is directed toward thesurface of the conductor. What is the charge density eta on the surface of the conductor at thatpoint?

Answer 1

Answer:1) d - it's always zero

2) a- 0

3) eta = - epsilon_0E

Explanation:

1) When a conductor is placed in an external electric field, the charges will accumulate to the two ends of the conductor depending on the direction of the field. As a result of this charge accumulation, the inside field develops and cancels with the outside field. Leaving the net field is always zero

2) we already know from answer 1, that there is a zero net electric field inside a conductor; therefore, if you surround any internal point with a Gaussian surface, there will be no flow at any point on this surface, and hence the surface will enclose zero net charge. Therefore, the charge density must be zero everywhere inside the conductor.

3) the charge density will be given as:

eta = - epsilon_0E