MEDI 11002 Lecture Notes - Lecture 3: Ferromagnetism, Magnetism, Magnetic Domain
CHAPTER 3 – UNDERSTANDING ELECTROMAGNETISM
- Magnetic field – a region around a magnetic material or moving electric charge
within which the force of the magnetism acts.
- The two ends of a magnet are
referred to as its magnetic poles.
Like magnetic poles repel each
other while unlike magnetic poles
attract each other.
like poles repel while unlike
poles attract
- Magnetic domains
o Magnetic materials are made up of areas (domains) of tiny particles which
themselves act as tiny magnets
o When these domains are aligned then it is said that the material is
magnetised.
- A magnet suspended so that it’s free to rotate horizontally will always align itself
in a North-South direction.
- Magnets are dipolar and the field around the magnet is called a dipole field
- Magnetic field lines are represented as arrows that flow out from the North pole
and into the South pole. Internally, the magnetic field flows from the south pole
to the north pole, completing the loop. If a compass was placed at any point in
the space around the magnet, it’s needle would align with the field line.
- Conventional current is a flow of a positive charge around a circuit or trhough a
space, and electron current is a drift of negative charge in a particular direction,
In electromagnetism, it is a convention to use the direction of the conventional
current as the direction of current flow → the electric current is creating a
magnetic field
- Ferromagnetic materials – having a high susceptibility to magnetization, the
strength of which depends on that of the applied magnetizing field, and which
may persist after removal of the applied field. This is the kind of magnetism
displayed by iron, and is associated with parallel magnetic alignment of
neighbouring atoms.
- RIGHT HAND RULE FOR MAGNETIC FIELD:
o Thumb – current
o Fingers – curl in direction of the field
- Oersted and Ampere discovered the relationship between current and magnetic
field.
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Document Summary
Magnetic field a region around a magnetic material or moving electric charge within which the force of the magnetism acts. The two ends of a magnet are referred to as its magnetic poles. Like magnetic poles repel each other while unlike magnetic poles attract each other. (cid:498)like poles repel while unlike poles attract(cid:499) Magnetic domains: magnetic materials are made up of areas (domains) of tiny particles which themselves act as tiny magnets, when these domains are aligned then it is said that the material is magnetised. in a north-south direction. Magnets are dipolar and the field around the magnet is called a dipole field. A magnet suspended so that it"s free to rotate horizontally will always align itself the space around the magnet, it"s needle would align with the field line. Magnetic field lines are represented as arrows that flow out from the north pole and into the south pole.
