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Home Concept Builders Static Electricity Conductors and Insulators Help Help 14

Conductors and Insulators - Questions 14 Help

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 four similar versions of this question. Here is one of the versions:

Version 1:
Object A is an insulator. Objects B and C are conductors. All three are neutral. Object C is touched by a positively-charged, conducting sphere. When the sphere is pulled away, what charge do the three objects have?

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

  • Identify whether Object A, Object B, and Object C are conductors or insulators.
  • Identify whether Object A (or C) is being touched by neutral ground or by a charged object.


What's Happening?
When a charged conductor is touched to a neutral conductor, there is a flow of electrons between the two conductors, resulting in the neutral object acquiring a charge. The process is known as charging by conduction or charging by contact. The type of charge acquired by the neutral object is identical to the type of charge on the charged object. Only conductors can conduct their charge to other conductors in this manner. Insulators cannot be charged by conduction since such materials prevent the flow of electrons from atom to atom across their surface.

Once a conductor acquires an excess of charge, that charge distributes across the entire surface of the conductor. If other conductors are directly connected to this charged conductor, then the excess charge will continue to distribute itself to the other directly-connected conductors. Insulators prevent this charge distribution process 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)

Concept Builder Teacher Notes Directions