Electric magnetism
Connection between electric and magnetic phenomena (1820 Hans Christian Oersted)
- current-carrying wire produces a magnetic field
- stationary charges do not produce magnetic field
Direction of the magnetic field produced by
currents: right-hand rule
Different field patterns can be produced by bending the wire,
All magnetic fields originate from current loops (Andre Ampere)
- the currents can be at microscopic level, originating from the
rotation of elementary charges
- the macroscopic magnetic properties of an object are determined
by the combined effects of these atomic level magnets
- if the orientation of the atomic magnets is random --> the object has no net magnetization (the same if no atomic magnet exist)
- if the atomic magnets are aligned --> the object is magnetized