What is Magnetism?

Properties of Magnets An unusual rock discovered City of Magnesia Contained mineral called magnetite (source of iron ore) Also attracted or repelled other magnetic rocks If rock swings freely, one part points to North Star / lodestar Magnetic rocks = lodestones

Magnetic Poles No matter the shape Two ends called poles: pole that points toward north is the NORTH POLE. The other is the SOUTH POLE. Opposite poles attract / Likes poles repel

Magnetic Force Attraction or repulsion between magnetic poles (pull or push) Produced when magnetic poles interact Force is strongest at the poles

Magnetic Fields area of force exerted all around magnet, strongest at poles Magnetic field lines (invisible) around magnet Lines leave from N pole, curve around the magnet, return to S pole (N→S) Closer the lines, the stronger the field HOW CAN WE TELL IF THE LINES ARE INVISIBLE?

See effects using iron filings Single magnetic field = 1 magnet combined magnetic fields = 2 or more magnets Notice where there is overlap & no field lines. Why?