12: Magnetism and the Motor Effect

current-carrying wires

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

electric motor

a current-carrying coil of wire in a magnetic field where the 2 sides of the coil that are perpendicular to the magnetic field experiance forces in opposite directions

electromagnet

a solenoid with an iron core

force on a wire

when a current cuts across a magnetic field, a force that is proportional to the current and length of the wire is exerted on it

fleming’s left-hand rule

thumb is force, first finger is field and second finger is current for motors

induced magnet

a material that becomes a magnet when it is placed in a magnetic field but loses it’s magnetism when removes

like magnetic poles

when matching poles of a magnet are brought near each other they repel

magnetic field

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

magnetic field lines

lines that show the strength and direction of a magnetic field. they point from north to south and their concentration represents the magnitude of the field

magnetic materials

iron, steel, cobalt and nickel

magnetic poles

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

permanent magnet

a magnet that produces its own magnetic field

solenoid

a wire wrapped into the shape of a coil, that has a strong and uniform magnetic field inside of it

tesla

the unit of magnetic flux density

unlike magnetic poles

opposite poles attract

uses of temporary magnets

speakers, generators and motors

uses of permanent magnets

computers, cars, compasses

right-hand grip rule

where the thumb and the fingers represent either the magnetic field or the current

magnetic forces

forces due to interactions between magnetic fields

force on a conductor at right angles to a magnetic field carrying a current =

= magnetic flux density x current x length