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 north-seeking 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.

Earth is a giant magnet, that is, the Earth produces a magnetic field. 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 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