Download Magnetic Forces

Magnetic Forces
The oldest instrument in the world is
the ancient Chinese compass
The plate bears Chinese characters
which denote the eight main directions
of: North, North-East, East, etc.
What is Magnetism?
Magnetism is the force of attraction
between magnets and magnetic
objects
Magnetism continued…
The invisible lines of force in the space
around a magnet that push or pull on some
things but have no effect on other things.
(Force at a distance)
What do magnetic lines of force
act upon?
Let’s consider different materials/scenarios:
·Non-metals: Not effected
· Most metals: Not effected
· Iron-containing materials: Effected (attracted)
· Opposite poles: Attracted
· Like poles: Repelled
Characteristics of Magnets
· Every magnet has two poles: North and South
· Every magnet has a magnetic field around it
The magnetic field is lines of force running from the northseeking pole to the south-seeking pole of the magnet
The World’s Largest Magnet
What do you know of that has a
North and South pole?
·The Earth is one giant magnet. It has two magnetic
poles and is surrounded by a magnetic field.
· This magnetic field is what causes the needle of a
compass to point in different directions and causes the
poles of a magnet to point either North or South
Do opposites attract?
Do like charges repel?
Yes. You remember electrons behavior…are there similarities?
The north and south-seeking poles of two magnets attract each other
- magnetic force pulls them together.
If you bring two of the same poles together, they repel.
A Confusing Thought…
Earth is a giant magnet, that is, the Earth produces a
magnetic field.
The North end of a magnet is attracted to the GEOGRAPHIC
north pole, which is where the opposite pole must be…
So, the magnetic South Pole is in GEOGRAPHIC North and the
magnetic North Pole is in GEOGRAPHIC South.
Earth's base magnetic field is similar to
that of a giant bar magnet. The solar
wind warps this base field into a slightly
different shape. However, in either case,
Earth's magnetic field lines come
together at the planet's poles... which is
why compasses work, and is also why
the aurora are most frequently seen
near the North and South Poles.
End of part 1