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