Physics / Unit 10: Magnetism and Modern Physics
10.1 Magnets and Magnetic Fields
Notes
Every magnet has a north and a south pole. Like poles repel; unlike poles attract.
- Poles always come in pairs: cutting a magnet in half gives two smaller magnets, each with N and S.
- A magnetic field surrounds a magnet. Field lines point out of north and into south, and are closest together where the field is strongest.
- Magnetic field strength is measured in teslas (T).
- Earth acts like a giant magnet. A compass needle's north pole points toward Earth's geographic north, which is near a magnetic south pole.
- Iron, nickel and cobalt are strongly attracted to magnets (ferromagnetic).
Practice
A bar magnet is cut in half. What do you get?
Magnetic poles cannot be separated.
Near a bar magnet, where is the magnetic field strongest?
Field lines crowd together at the poles.
The north end of a compass needle points toward Earth's geographic North Pole. What kind of magnetic pole is located there?
Opposites attract, so the needle's north is pulled toward a magnetic south pole.
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