Magnets are made from magnetic materials.
These are metals that can be magnetised or
will be attracted to a magnet. Most materials
are not magnetic, but iron, cobalt and nickel
are magnetic. Steel is mostly iron, so steel is
When an electric current flows in a wire it
creates a magnetic field around the wire.
By winding the wire into a coil we can
strengthen the magnetic field.
Electromagnets are made from coils like
REMEMBERED FACTS:electromagnetic fields are created when an electric wire is wrapped around an magnetic source. We
can make it stronger by wrapping the wire around the magnet in a coil.
We can make an electromagnet
stronger by doing these things:
wrapping the coil around an iron
core adding more turns to the
coil increasing the current
flowing through the coil.
The magnetic field around an
electromagnet is just the same as the
one around a bar magnet. It can,
however, be reversed by turning the
battery around. Unlike bar magnets,
which are permanent magnets, the
magnetism of electromagnets can be
turned on and off just by closing or
opening the switch.
REMEMBERED FACTS: electromagnets
have the same
magnetic fields as
bar magnets, except
that they can be
reversed and turned
They fill the space around a magnet where
the magnetic forces work, where they can
attract or repel magnetic materials.
CANNOT BE SEEN.
Although we cannot see magnetic
fields, we can detect them using iron
filings. The tiny pieces of iron line up in
a magnetic field.
REMEMBERED FACTS: magnetic fields cannot be seen so we use iron filings to
detect where they are. Iron filings can attract or repel magnets. The magnetic field
lines flow from north to south, they are more concentrated at the poles.
the field lines have
arrows on them the field lines come out of N
and go into S the field lines are more
concentrated at the poles.
Electrical energy can
reactions. This happens
in a chemical process
1 Pieces of metal, called electrodes,
are placed in the water. 2 A little
sulphuric acid is added to the water to
make the process work. 3 The
electrodes are connected to a battery. 4
The water completes the circuit between
the electrodes and current flows
Where the electrodes come into contact with the
water chemical changes take place, producing
bubbles of gas. Oxygen at one electrode and
hydrogen at the other one. This electrolysis
produces twice as much hydrogen as oxygen. They
are both useful gases used in many chemical
processes in industry.
REMEMBERED INFORMATION: electrosis is a chemical reaction caused
by an electrical current touching water.
When water touches the electrical circuit,
it creates a chemical reaction where the
electrodes and water mix, causing oxygen
to appear at one electrode, and hydrogen
at the other. Twice as much hydrogen is
created the oxygen.