Physics Topic 7 - Magnetism and Electromagnetism

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alternator

device that makes use of the generator effect to generate AC

attraction

opposite poles will experience a force towards each other. The force between a magnet and magnet material is always one of attraction

current carrying wire

when current flows through a wire, a magnetic field is generated around it. The strength of the field is dependent on the magnitude of the current and the distance from the wire

dynamo

device that makes use of the generator effect to generate DC

electric motor

a current-carrying coil of wire in a magnetic field. The two sides of the coil that are perpendicular to the magnetic field experience opposite forces causing rotation

electromagnet

a solenoid with an iron core

Fleming’s Left Hand Rule

force (thumb), current (second finger), magnetic field (first finger) when a current-carrying wire is placed in a magnetic field

Generator Effect

When there is relative motion between an electrical conductor and a magnetic field, a P.D will be induced across the ends of the conductor. A current will flow if the conductor is part of a complete circuit

induced magnet

material that becomes a magnet when it is placed in an existing magnetic field, but loses its magnetism quickly when removed from the field

magnetic compass

device containing a small bar magnet that points in the direction of the Earth’s magnetic field

Magnetic field line

lines representing the strength and direction of a magnetic field. The field line direction at any point is in the direction that a force would act on another north pole if placed at that point

magnetic field

region around a magnet in which another magnet or magnetic material will experience a force

magnetic materials

iron, steel, cobalt and nickel

magnetic poles

regions of a magnet where the magnetic forces are at their strongest

microphone

device that uses the generator effect to convert the pressure variations of sound waves into variations in the electrical current of a circuit

motor effect

when a current-carrying wire is placed in a magnetic field, a force will be experienced between the wire and the magnet responsible for the field

permanent magnet

magnet that produces its own magnetic field

repulsion

like poles will experience forces in opposite directions

solenoid

a wire wrapped into the shape of a coil that has a strong and uniform magnetic field in it. Its magnetic field strength can be increased with an iron core

step down transformer

transformer that has a smaller P.D in the secondary coil that in the primary core

step up transformer

transformer that has a larger P.D in the secondary coil than in the primary core

Tesla

unit of magnetic flux density

transformer

iron core with a primary and secondary coil of wire wound around opposite ends