Question About a Test Charge Near a Conductor

[nmfowlkes]

Homework Statement

A positive test charge is brought near to, but not touching, a conducting sphere that is connected to the ground. Both objects remain at rest in the positions shown above. Charge begins to flow from the ground to the sphere. Which of the following statements best describes when charge stops flowing, and provides justification for the claim?

A. Charge will flow until the electric field at the surface of the sphere is equivalent to the electric field of the test charge, because then the excess charge on the surface of the sphere will be equal to the charge of the test charge.

B. Charge will flow until the electric field at the surface of the sphere is equivalent to the electric field of the test charge, because then the net force on all charges on the surface of the sphere will be zero.

C. Charge will flow until the potential at the surface of the sphere is the same as the potential of the test charge, because then the net force on all charges on the surface of the sphere will be zero.

D. Charge will flow from the ground to the sphere until the potential is the same everywhere within the sphere, because then the excess charge on the surface of the sphere will be equal to the charge of the test charge.

E. Charge will flow from the ground to the sphere until the potential is the same everywhere within the sphere, because then the net force on all charges on the surface of the sphere will be zero.

Relevant Equations

This is a conceptual problem. Equations are not relevant.

I am confused because I thought this was a method of charging a conductor. Why would the system be reaching a state of equilibrium?

 

[hutchphd]

You bring up the charge and then count to ten...Equilibrium for as long as you keep the test charge stationary . What does it look like and why?

 

[kuruman]

I am confused because I thought this was a method of charging a conductor.

It is only part of the method of charging a conductor by induction. There are additional steps which are not taken here.

Why would the system be reaching a state of equilibrium?

Because if it is not in equilibrium, charge will flow until it reaches equilibrium.

The wording in the first two choices bothers me. I don't know how to tell that an electric field is "equivalent" to another electric field. Is this something that is discussed in wherever you found this question?