IEB Grade 12 Electrodynamics notes

1.
Magnetic fields
1.
Electromagnetism
1. 1
Magnetic fields
↳
a
region in space in which a magnetic object experiences a force
↳
produced by electric currents , which can be current in wires for microscopic currents

associated with electrons in atomic orbitals)

↳ exists around conductor
a permanent magnet or a current
carrying
-




↳ and direction of the
magnetic field lines
visually represent the strength magnetic field
↳ lines are continuous closed loop
,
forming a


↳ direction of
magnetic field is from the north pole to the south pole of the magnet


1. 1.1 The field around straight current conductor
magnetic a
carrying




Right hand rule


your right hand
↳ hold the conductor in with thumb in the direction of
your pointing
conventional current (+ to -


) and
,
then
your fingers will curl in the direction of the


magnetic field




The around conductor detected
magnetic field a current
carrying by
-




small compasses

, The magnetic field around
1.1.2 a
single loop of wire

use the
right hand rule to
verify the

direction of the
magnetic field lines




1. 1.3 The magnetic field around solenoid
a current
carrying
↳
a solenoid is a cylindrical coil of wire which acts as a
magnet
electric current
when
carrying




↳ this is if the direction of the current
an
electromagnet in the

↳ its field is like that of a bar magnet solenoid is reversed then ,
the direction of
↳ the field inside
is strongest on the the magnetic field is also reversed




Right hand rule : Hold the solenoid in
your right 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

1.1.4 The magnetic field between two parallel magnets

, 2. TheMotOref
2. 1
Magnetic force on
moving charges
↳
conventional current is the rate of flow of positive charge from the positive terminal

of the cell to the terminal
negative
↳ when a current -




carrying conductor is placed in a
magnetic field ,
the
charges
the conductor experience magnetic force
moving along a

↳
this force is greatest when the conductor is placed at right angles to


14 )
the
magnetic field ( figure
↳
the direction of the force is at right angles to both the direction of the

current and the
magnetic field ( figure 14 )
↳ the
force on the conductor will be zero when the direction of the current is


parallel to the
magnetic field lines

↳ the direction of conductor
the force on the current
carrying in the
magnetic field is
-




found using Fleming 's left hand motor rule




2. 1.1
Fleming 's left hand motor rule

↳ Used
find the direction of force conductor in
to the on a current
carrying a
magnetic
-




field
↳ the field
first finger must point in the direction of the magnetic
(B) ( from north to south )

↳
the second finger must point in the direction of the conventional

current ( I ) (from + to -

)

force (F)
↳ the thumb will point in the direction of the