Grade 12 Physical Science:
Electrodynamics:
MAGNETIC FIELDS:
A magnetic field is a region in space in which a magnetic object experiences a force.
• Magnetic fields are produced by electric
currents, which can be currents in wires.
• A magnetic field exists around a permanent
magnet.
• Magnetic field lines are useful for visually
representing the strength and direction of the
magnetic field.
• Magnetic field lines are continuous lines,
forming closed loops.
• The direction of the magnetic field is from the
north pole to the south pole of a magnet.
The magnetic field around a straight current carrying conductor:
If a current is passed through a straight conductor, a magnetic field is created.
The magnetic field lines are concentric circles centred on the
conductor.
The Right-Hand Rule:
The right-hand rule is used to find the direction of the magnetic field
lines.
Hold the conductor in your right hand with your thumb pointing in the
direction of conventional current and then your fingers will curl in
the direction of the magnetic field.
Thumb points from positive to negative (conventional current)
• If the direction of the current is towards you (i.e. out of the page), this is shown as
a dot on the paper.
This means that your fingers will curl anticlockwise.
• If the direction of the current is away from you (i.e. into the page), this is shown as
a cross on the paper.
This means that your fingers will curl clockwise.
, The magnetic field around a single loop of wire:
Use the right-hand rule to verify the direction of the
magnetic field lines.
The magnetic field around a current carrying solenoid:
A solenoid is a cylindrical coil of wire which acts as a magnet when carrying electric
current.
When a current is passed through the solenoid, the magnetic field is produced.
If the current in the solenoid is reversed, then the direction of the magnetic field is
also reversed.
Right-hand thumb rule:
Hold the solenoid in your hand so that your fingers curl in the direction of the
conventional current. Your thumb will then point in the direction of the north pole.
The magnetic field between two parallel magnets:
Electrodynamics:
MAGNETIC FIELDS:
A magnetic field is a region in space in which a magnetic object experiences a force.
• Magnetic fields are produced by electric
currents, which can be currents in wires.
• A magnetic field exists around a permanent
magnet.
• Magnetic field lines are useful for visually
representing the strength and direction of the
magnetic field.
• Magnetic field lines are continuous lines,
forming closed loops.
• The direction of the magnetic field is from the
north pole to the south pole of a magnet.
The magnetic field around a straight current carrying conductor:
If a current is passed through a straight conductor, a magnetic field is created.
The magnetic field lines are concentric circles centred on the
conductor.
The Right-Hand Rule:
The right-hand rule is used to find the direction of the magnetic field
lines.
Hold the conductor in your right hand with your thumb pointing in the
direction of conventional current and then your fingers will curl in
the direction of the magnetic field.
Thumb points from positive to negative (conventional current)
• If the direction of the current is towards you (i.e. out of the page), this is shown as
a dot on the paper.
This means that your fingers will curl anticlockwise.
• If the direction of the current is away from you (i.e. into the page), this is shown as
a cross on the paper.
This means that your fingers will curl clockwise.
, The magnetic field around a single loop of wire:
Use the right-hand rule to verify the direction of the
magnetic field lines.
The magnetic field around a current carrying solenoid:
A solenoid is a cylindrical coil of wire which acts as a magnet when carrying electric
current.
When a current is passed through the solenoid, the magnetic field is produced.
If the current in the solenoid is reversed, then the direction of the magnetic field is
also reversed.
Right-hand thumb rule:
Hold the solenoid in your hand so that your fingers curl in the direction of the
conventional current. Your thumb will then point in the direction of the north pole.
The magnetic field between two parallel magnets:
