What Happens to an Insulator When a Charged Metal Ball Approaches?

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When a negatively charged metal ball approaches an insulator, the insulator's charges rearrange to create a dipole moment, resulting in a weak attraction to the ball. The negative charge of the ball attracts the positive charges in the insulator while repelling its negative charges. This behavior contrasts with conductors, where charge can move freely. The discussion emphasizes that while the insulator does not transfer charge effectively, it still exhibits a weak attraction due to charge polarization. Understanding this concept is crucial for grasping electrostatic interactions involving insulators.
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1. i have the answer, but just don't understnad it
A small metal ball is given a negative charge, then brought near (i.e., within a few millimeters) to end A of the rod. What happens to end A of the rod when the ball approaches it closely this first time?
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Select the expected behavior.

X strongly repelled
X strongly attracted
weakly attracted
X weakly repelled
X neither attracted nor repelled

The Attempt at a Solution


Well, i first figured that the negatively charged ball and the side A of the rod would weakly repel, seeing that there are two negative charges, and one postive charge, a ratio of 2:3 negative.
-that answer was wrong
then i thought that since it was an insulator, and is not even really charged (having a nuetral charge as a whole) it would be neither attracted nor repelled.
-also wrong.
-so, an insulator does not transfer charge well, but i don't see how this helps me answer the question really.

so it's weakly attracted because the insulator rearranges to give a small dipole moment, which makes it weakly attracted?
 
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Right. The negative charge on the ball will attract the positive charges on the rod and repel the negative charges.

The image of the rod is to show you that there is no overall charge on the rod.

Have you had any lab practice using gold leaf electroscopes? Very instructive!
 
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