Magnetism
Physics · चुंबकत्व · 15 facts
Magnet: attracts iron/cobalt/nickel; North and South poles
Like poles repel; unlike attract; strongest at poles
Earth is giant magnet; compass shows N-S direction
Electromagnet: current+coil+iron core; temporary
Uses: bells, cranes, MRI, speakers, motors
Oersted(1820): current produces magnetic field around conductor
Fleming Left Hand: force on conductor in field (Motor)
Fleming Right Hand: induced current direction (Generator)
Motor: electrical to mechanical; Generator: mechanical to electrical
Faraday Law: changing magnetic field induces EMF
Field lines: N to S outside; never cross
Magnetic materials: ferromagnetic(Fe), paramagnetic(Al), diamagnetic(Cu)
Breaking magnet gives two complete magnets with N and S poles each
Magnetic declination: angle between geographic North and magnetic North
Transformer: changes AC voltage using mutual induction; does not work with DC