Electrostatic Charge

Neutral Objects.

We know that like charges repel and unlike charges attract
but what about neutral (uncharged) objects?

Are Neutral Objects Attracted to Charged Objects?

It is found that a charged object, whether positive or
negative, may attract uncharged objects. For
example a charged plastic comb will pick up small pieces
of paper. You can try this yourself. Just charge
the comb by combing your hair! Hair is a good insulator.


What is Happening to make the Neutral Object Attract?

It is thought that when a negatively charged object gets close
to an uncharged object, electrons in the uncharged object
are repelled, leaving the positive charges behind. These positive
charges are then attracted to the negatively charged object.
This is shown in the picture below.

Charged Rod Attracting a Neutral Object

If the rod was positively charged,
then it would attract electrons in the neutral object
and so the two would still attract each other
(just reverse the + and - in the picture above).

The small number of charges shown is an oversimplification
since in reality there are millions and millions of atoms in a
tiny piece of paper, each with its own electrons and protons.
When we draw the rod with a few negative charges, it means
that the rod has a few more negative than positive charges.

The fact that charged objects are attracted to neutral objects
is used to improve the efficiency of crop spraying.

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