Fundamentals

Materials can be categorized as being conductors or insulators. Conductors are those materials that allow the free flow of electrons from atom to atom across their surface. Insulators prevent the free flow of such electrons.  This property makes the behavior of conductors quite different than that of  insulators when they are touched to a charged object or to the ground.
 

There are two similar versions of this question. Here is one of the versions:

Version 1:
Object A is a conductor. It has a positive charge. It is touched to the ground. When the ground is pulled away, what charge does Object A have?

 

How to Think About This Situation:

Like all questions in Conductors and Insulators, you will need to ...

  • Identify whether Object A (and B and C) is a conductor or an insulator.
  • Identify whether Object A (or B or C) is being touched by neutral ground or by a charged object.


What's Happening?
When a charged conductor is touched to the ground, it's charge is removed by means of electron flow between the ground and the object. Only conductors can conduct their charge in this manner. Insulators are unable to transfer charge in this manner since such materials prevent the flow of electrons from atom to atom across their surface.
 

Try these links to The Physics Classroom Tutorial for more help with understanding the process of conductors, insulators, conduction, and grounding. Links to the corresponding videos are also included:

Conductors and Insulators  (view Video)

Charging by Conduction  (view Video)

Grounding - The Removal of Charge  (view Video)
 


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