Magnetism

History: The study of magnetism dates back to before 600 B.C., with serious investigations beginning in the 20th century.
Key Figures:
- William Gilbert: First systematic investigation of magnetism; discovered Earth is a weak magnet.
- Hans Oersted: Linked electricity and magnetism.
- James Clerk Maxwell: Established that electricity and magnetism are aspects of the same fundamental force field.
Properties of Magnetic Lines of Force:
- Originate from the north pole and end at the south pole; form closed loops.
- Indicate the direction of the net magnetic field at a point.
- The density of lines indicates the strength of the magnetic field.
Key Facts:
- Every magnet has a north and south pole.
- Breaking a magnet yields independent magnets; isolated monopoles do not exist.
- Like poles repel, unlike poles attract.
- A freely suspended magnet aligns in a North-South orientation.
Magnetic Density:
- Density indicates the strength of the magnetic field; magnetic flux defines the total lines of force through a unit area (SI unit: Weber).
Bar Magnet Behavior:
- A bar magnet functions as a magnetic dipole with defined pole strengths.