Magnetism And Electromagnetism

magnetic force

interactions between magnetic fields

induced magnetism

When a magnetic material is placed in a magnetic field and it is temporarily turned into a magnet

material for temporary magnet

soft core/ iron

material for permanent magnet

hard core/ steel

nonferrous properties

will never be attracted or repelled when brought in a magnetic field

ferrous properties

will always be attracted when brought in a magnetic field

magnet

will either be attracted or repelled when brought in a magnetic field, has opposite north and south poles

methods of demagnetisation

heating until glowing red, hitting with a hammer, using alternating current in a coil

magnetic polar behaviour

opposite poles attract, like poles repel

magnetic field

a region in which a magnetic pole experiences a force

direction of field lines on a bar magnet

always goes from north to south

ways to see the field lines

iron filings, compass plotting

spacing in the lines of a magnetic field

shows the relative strength of the magnetic field

properties of a uniform magnetic field

equally spaced, parallel, straight lines

ferrous materials

anything containing iron, nickel, or cobalt

hard material

will retain its magnetisation once magnetised ie. steel

soft material

easily lose their magnetisation, used in temporary/ electromagnets ie. iron

magnetic domain in a magnet

all domains are oriented in the same direction

magnetic domain in a non-magnet

domains are oriented randomly

stroking method

stroking an unmagnetised material with a magnet aligns all of the domains in the same direction and creates a magnet

electrical method

the direct current aligns all of the domains in the same direction and creates an electromagnet

N pole

North-seeking pole of a magnet

electric current in a conductor

produces a magnetic field around it

straight wire magnetic field

concentric circles centred on the wire

increasing magnetic field stregth

increases the current running through the wire, increasing the number of turns on a coil, or adding a soft core to a solenoid

flat circular coil field

two straight wire magnetic fields, with one straight line through the centre

solenoid

a coil of wire carrying an electric current through it

solenoid magnetic field

similar to a bar magnet with two poles at each end of the coil

electromagnet

a coil carrying a current wrapped around a soft iron core

lost magnetism in an electromagnet

when the current is turned off