A uniform magnetic field is shown by straight lines
Uniform field line
Non uniform field line
Magnetic field line: An invisible line which
shows direction of a magnetic field.
Always flow form NORTH to SOUTH
Rules: 1) Opposite Poles attract
2) Like poles repel 3) Field lined
always flow from North to South
3 magnetic metals: IRON, COBALT, NICKEL
Ferromagnetic metals (metals made out of iron)
contains domains which are tiny crystals which
have their own magnetic field.
When the metal is magnetised, these domains line up
Magnetically HARD materials:
Domains are lined-up and fixed in
place
Example: Steel
Magnetically SOFT materials:
Domains are free to move and
change direction
Can increase strength of field by stroking soft
material with a magnet
Example: soft iron or pure iron
Electromagnetism
RIGHT HAND RULE FOR WIRES
Can be used to figure out the direction
of the magnetic field
Perfect Electromagnet consists of: NICKEL, IRON
COBALT (Core) and LOTS and LOTS of COILS
USES OF ELECTROMAGNETS: 1) Scrap yard
crane, 2) MRI machines (magnetic resonance
imaging, 3) The electric bell, 4) Circuit Breaker
Motor Effect
When a current carrying conductor, carrying an electric current is
placed in the magnetic field, it will experience a force provided that
the conductor (wire) is not placed parallel to the field lines.
The force increases if: the strength of the magnetic
field is increased or the current is increased
The direction of the force is reversed if either: The
direction of the current or the direction of the
magnetic field is reversed
FLEMINGS LEFT HAND RULE!
NOTE: Magnetic field direction is NORTH TO SOUTH
and Current direction is PLUS TO MINUS