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9Sci CH22
9th Science CH22 Magnetism and Its Uses
| Term | Definition |
|---|---|
| alternating current (AC) | electric current that reverses its direction in a regular pattern;the 60-Hz AC in our homes changes direction 120 times each second |
| ammeter | a galvanometer that measures electrical current passing through in amperes; connected in series with the circuit |
| direct current (DC) | electrical current that flows in only one direction through a wire |
| electric motor | a device that contains a rotating electromagnet that changes electrical energy to mechanical energy |
| electromagnet | strong temporary magnet made by inserting an iron core into a wire coil and passing an electric current through the coil |
| electromagnetic induction | process by which electrical current is induced in a wire when it is moved through a magnetic field |
| generator | a device that uses electromagnetic induction to induce electrical current by rotating loops of wire through a magnetic field |
| magnetic domain | groups of atoms with aligned magnetic poles |
| magnetic field | the region around a magnet where magnetic forces act |
| magnetic pole | the two ends of a piece of magnetic material where the magnetic forces are strongest, labeled north pole (N) and south pole (S) |
| magnetism | a property of some materials in which there is a force of repulsion or attraction between certain like and unlike poles |
| superconductor | a supercooled material that has no electrical resistance ; a current can flow indefinitely through a superconductor without losing energy |
| transformer | a device that can increase or decrease the voltage of an alternating current |
| voltmeter | a galvanometer that measures potential differences in volts and is placed in parallel across a part of the circuit |