Surface charge on a conductor due to a charged rod 'q'

In summary, the question asks about the total surface charge on a perfect conductor when a charged rod is placed at a distance from it. The attempt at a solution explains that the conductor will have a negative charge on its surface due to the presence of the charged rod, and this charge will increase until the total electric field on a point charge at infinity becomes zero. This explanation also addresses the concern about the distance 'd' and mentions that the charge density on the conductor will decrease as the distance increases. It is also noted that this explanation applies even if the conductor is not perfect (has a finite conductivity).
  • #1
iVenky
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Homework Statement


A charged rod of charge 'q' is at a distance 'd' from a perfect conductor as shown below.
What's the total surface charge on the conductor?
upload_2018-12-24_23-54-41.png

2. Homework Equations

I tried to solve this without equations.

The Attempt at a Solution


[/B]
Basically, as long as there is E field due to +q, it can draw a negative charge from the conductor to the surface. This would stop once the total E field on a point charge at infinity goes to 0. This should happen when the total charge on the surface is exactly -q. Is this explanation correct?

However, what's bothering me is the non-dependence on distance 'd'. If d-> ∞, then I wouldn't expect 'q' draw any charge on the conductor since E field would be zero at d-> ∞. Then what's wrong here?
Also, does this explanation work even if this conductor is not perfect (has a σ≠∞)
 

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  • #2
iVenky said:
If d-> ∞, then I wouldn't expect 'q' draw any charge on the conductor since E field would be zero at d-> ∞. Then what's wrong here?
The charge density becomes lower as the induced charge will be spread over a larger portion of the conductor.

iVenky said:
Also, does this explanation work even if this conductor is not perfect (has a σ≠∞)
The problem only deals with the static situation, i.e., the situation after a long time has passed. With finite conductance that will take longer to achieve for a non-perfect conductor, but the end result would be the same.
 
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Related to Surface charge on a conductor due to a charged rod 'q'

1. What is surface charge on a conductor?

Surface charge on a conductor refers to the accumulation of excess charge on the surface of a conductor due to the presence of an external charge.

2. How is surface charge on a conductor calculated?

The surface charge on a conductor is calculated by dividing the total charge on the conductor by its surface area.

3. What is the role of a charged rod in creating surface charge on a conductor?

A charged rod can induce a surface charge on a conductor by attracting or repelling charges in the conductor, leading to an accumulation of charge on the surface.

4. Can a conductor have a non-zero surface charge in the absence of a charged rod?

Yes, a conductor can have a non-zero surface charge in the absence of a charged rod if it is in contact with another charged object or if it is charged by an external source.

5. How does the distance between the charged rod and the conductor affect the surface charge?

The surface charge on a conductor due to a charged rod decreases with increasing distance between the two objects. This is because the electric field strength decreases with distance, leading to a weaker induced charge on the conductor's surface.

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