| Static electricity (electrostatics) and magnetism |
Static electricity and magnetism are both examples of forces that can excert a push as as well as a pull
Static Electricity
If certain insulators get rubbed against a different surface they pick up an
electrostatic charge.
Two objects with the SAME charge will REPEL each other
eg two nylon rods with the same charge repel repel each other
Two objects with DIFFERENT charges will attract each other
eg a charged nylon rod is attracted to an acetate rod
or When a balloon is rubbed against a a woollen jersey it picks up a static charge. The charged balloon is attracted to the neutral ceiling.
|
Unlike
poles attract |
The Van De Graaff generator:
is a machine for producing a very high voltage (up to 15 million volts.)
Magnetism
If a substance is attracted to a magnet it is said to be magnetic.
A magnetic substance must contain iron, cobalt or nickel.
Magnets have two poles.
The north seeking pole (N) and the south seeking pole (S).
The pole of the magnet is where the magnetism is strongest.
Two poles that are different will be attracted.
(ie a North pole will be attracted to a South Pole or to another piece of iron,
cobalt or nickel)
Two poles that are similar will repel each other.
(ie a north seeking pole is repelled by another north seeking pole)
|
Unlike
charges attract |
| Lines of invisible force called magnetic field lines run from the N pole to S pole. |
One way to plot a magnetic field is to lay a piece of paper
over a magnet and sprinkle iron filings on the paper
Click here
to see the result.
Iron filings can also show the magnetic field lines between
two magnets
Click here
to see the result
A magnetic field can be shown to exist by bringing a magnet
near a compass.
This experiment
shows the magnetic field produced by sending a current through a length of wire
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