simple phenomena of magnetism
poles
like poles (N & N, S & S, + & +, - & -)repel, unlike poles (N & S, + & -) attract.
magnetic field lines
magnetic field lines are imaginary lines used to visualize the magnetic field. they emerge from the north pole and enter the south pole of a magnet. the distance between these lines indicate the strength of the magnetic field.
magnetic poles and forces
north pole (n pole) and south pole (s pole). like poles repel, opposite poles attract. magnetic forces exist between magnets and magnetic materials.
induced magnetism
process where magnetic materials become magnetized when placed in a magnetic field
types of magnets
temporary magnets: made of soft iron, lose magnetism easily when removed from magnetic field, used in electromagnets.
permanent magnets: made of steel, retain magnetism for long periods, do not easily lose their magnetic properties.
magnetic and non-magnetic materials
magnetic materials: iron, steel, cobalt, nickel.
non-magnetic materials: wood, plastic, paper, aluminium.
magnetic fields
magnetic field: region in which a magnetic pole experiences a force.
magnetic field lines: lines drawn to show direction and pattern of magnetic field, emerge from north pole and enter south pole, closer spacing indicates stronger field, plotted using compass or iron filings.
direction of magnetic field: direction at a point is the direction of force on north pole at that point.
magnetic field interactions
magnetic forces are due to interactions between magnetic fields. relative strength of magnetic field is represented by spacing of field lines. no two magnetic field lines ever intersect.
applications of magnetism
permanent magnets: loudspeakers, refrigerator doors.
electromagnets: electric motors, doorbells, relays.