all magnets have a ... and a ...
all magnets have a north pole and a south pole
the magnetic field flows from ... to ...
the magnetic field flows from the North pole (N) to the South pole (S)
what are ferromagnetic materials?
materials that can be magnetised, which are also the ones that are strongly attracted to a magnet
what are three examples of ferromagnetic materials?
iron, nickel, and cobalt
what are permanent magnets?
objects made from magnetised material and produce continual magnetic fields
what are three examples non-magnetic materials?
are all substances magnetic?
what test can you perform to discover whether a substance is magnetic?
get a sample of the substance and hold it against a magnet
if it attracts then it is magnetic
if if does not then it is non-magnetic
what do magnets do to other magnets?
repel and attract
what do magnets do to magnetic substances?
how can the shape of a magnetic field around a bar magnet be revealed? include safety precautions
put paper on cardboard ontop of two wooden blocks
place the magnet undereneath of the cardboard
place a white peice of paper ontop the carbdoard
sprinkle iron filings over the the paper
tap the paper with a pen to reveal the pattern of the magnetic field
safety: wear goggles, don't touch the iron filings, put the experiment into a white tray so you don't spill the iron
draw the shape of the magnetic field around a bar magnet
what is a magnetic field?
an area around a magnetic material or the moving electric charge through which the force of magnetism acts
what are magnetically hard substances?
substances that can be permanently magnetised
difficult to magnetise and demagnetise
these are often alloys of iron, nickel and cobalt
what are magnetically soft substances?
substances that can only be temporarily magnetised - cannot retain their magnetic properties
easy to magnetise and demagnetise
e.g. pure iron
what are magnetically hard substances used for?
to make permanent magnets
what are magnetically soft substances used for?
to make temporary magnets
what test would you perform to discover whether a metal bar is a magnet or not?
it will repel a known magnet
you are asked to sort a large pile of empty cans from one another
some are food cans (made of iron)
some are drinks cans (made of aluminium)
how would you go about doing this without looking at the labels?
use a magnet
iron is magnetically soft so it will be attracted to the magnet
aluminium is not attracted to the magnet and will be left in the pile
you are presented with three painted metal rods which are identical in appearance except that each is labelled with a letter A,B and C. You are told that one is a piece of soft iron, another is brass and the third is a permanent magnet
what tests would you carry out to decide which bar is which?
hold a magnet to the materials
the brass will not move as it is not magnetic
the iron will attract the magnet
the permanent magnet will repel the magnet
what does the term 'magnetic field line' mean?
'lines of force' - lines that show the size and direction of magnetic fields - they always point from North to South magnetic field
is magnetism induced in some materials? how?
some materials that are not magnetic can become magneticaly induced when they are close to a magnetic field
after some time they aquire magnetic property
this is because the magnetic field encouraged its electrons to align and form poles
what does a uniform magnetic field pattern mean?
the field lines are exactly parallel to each other
how do you use two permanent magnets to produce a uniform magnetic field pattern?
by keeping the opposite poles face each other
the region between the poles would establish magnetic field that would be uniform
draw the magnetic field lines for two North poles next to each other
draw the magnetic field lines for two South poles next to each other
which way do the arrows face when drawing magnetic field lines?
north = going away
south = going in
draw the magnetic field lines for one North pole and one South pole facing to each other
an object that produces a magnetic field which pulls on other magnetic materials and attracts or repels other objects
either of the two points of a magnet to and from which the lines of magnetic force are directed
The closer the magnet and the magnetic material get, the stronger/weaker the induced magnetism will be
The closer the magnet and the magnetic material get, the stronger the induced magnetism will be
what is the relationshpi between the distance between the magnetic field lines, magnetic strength and the force?
the closer the magnetic field lines, the stronger the magnetic field strength and the forces