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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.
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.
Links
Electrostatic Charge
Revision Questions
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