Transcript Magnetism Basics

Magnetism and Electricity
Principles of Physics
3 Dimensional Directions
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Current and Magnets
In the presence of moving charge (current) a compass will rotate
 so, current carrying wires exert magnetic force
When the wire is wrapped in a loop poles form on each side of it
For a stronger B-field
 more loops (solenoid)
 loops wrapped around a magnetic core (electromagnet)
More on how materials become magnetized…
Electrons move in tiny circular paths
generating their own magnetic fields
 Electrons are grouped in areas called
domains
 B-fields of electrons in each domain are
lined up
 Together they act as one stronger B-field
 The magnetic effect is even stronger when
domains line up.
More on how materials become magnetized…
 Materials that can become magnetized
have domains that can shift in order to
line up.
 High permeability = domains shift easily
 Low permeability = domains hard to shift
Force on a Current Carrying Wire
Current carrying wires placed near
a magnet can experience force
 force causes wire to move
 current must flow perpendicular
to the B-field
* single charges can also experience
a force in a B field
Force on a Current Carrying Wire
F = IlB
F = force (N)
I = electron flow (A)
l = length of wire (m)
B = Magnetic Field strength (Tesla = T = N/Am)
Example Problem
The current flowing in a 2.0 m wire is 100 A. The wire is
placed in a magnetic field of 0.003 T such that it is oriented
perpendicular to the field. Calculate the force experienced by
the wire.
F = IlB
F = 100 A(2.0 m)(0.003 T )
F = 0.6 N
Left Hand Rule
 Thumb = direction of e-flow
 Fingers = direction of B-field
 Palm = force
Current
(e- flow)
Force
Magnetic Field
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