1.  A magnet is a material
or object that produces a
magnetic field with a
North and South Pole.
Magnetism: an invisible
force that pushes or pulls
magnetic material.

2. H
I
S
T
O
R
Y
O
F
M
A
G
N
E
T
S

3.  Regions of atoms that
have the same magnetic
polarity (N/S Alignment).
 Mini-magnets.
 Unmagnetized Iron
 Magnetic domains point
in different directions.
 Magnetic fields cancel
each other out.
 Magnetized Iron
 Magnetic domains are
lined up in the same
direction
 Magnetic fields amplify
each other.

4. The direction of the magnetic force is
from NORTH to SOUTH

5. TWO UNLIKE POLES GIVE A TWO LIKE POLES
FORCE OF ATTRACTION TOGETHER WILL HAVE A
FORCE OF
REPULSION
Can you explain what the lines of
force show?
Where is the strongest part of
the field?
Where is the weakest part of
the field?

6. Small particles of iron filings are pushed into patterns by
a magnetic field. If we sprinkle iron filings on a piece of
paper over a magnet we can see...
The lines of force are very
close together here – the field
is very strong.
The lines of force are further
apart here – the field is weaker.
A line of force links one pole of a magnet to the other pole.

7. FOR EACH PICTURE IDENTIFY THE FORCE
ILLUSTRATED……………
A)
B)

8. MAGNETIC COMPASS
CONTAINS A MAGNET
THAT INTERACTS WITH
THE EARTH'S MAGNETIC
FIELD AND ALIGNS ITSELF
TO POINT TO THE
MAGNETIC NORTH AND
SOUTH POLES.

9. North magnetic
pole located at
south geographic
pole
South magnetic
pole located at
north geographic
pole.

10. Magnetic declination
•is the angle between
magnetic north and
geographic true north.
•Angle varies by location
•Ranges from 0⁰ to 25 ⁰

11. Electromagnet
 coil of wire that acts as a magnet when
an Electric
current is passed through
it.
 stops being a magnet when the current
stops.
 Often, the coil is wrapped around a core
of
ferromagnetic material like steel, this
enhances the
coils magnetic field.

12. an object made from a
material that is magnetized
&
creates its own persistent
magnetic field.
 Example
refrigerator magnet

13.  Levitating trains
(MagLev)
 Treatdepression &
chronic headaches
 Electric motors
 Stereo Speakers
 Credit Cards

15. •Produced by electric currents
•Defined as a Region where magnetic forces
can be detected.
•Has a North & South magnetic pole
•The SI unit for a large magnetic field is the Tesla
•The SI unit for a smaller magnetic field is the Gauss
•(1 Tesla = 10,000 Gauss).

16. The strength of a magnetic field (B) is
related to the amount of magnetic force (F)
that is applied to a moving test charge when
it is at a given location in the field.
B = F magnetic
qv
q = test charge magnitude
v = speed of the charge

17. A proton moving east experiences an upward force of 8.8 x
10-19 N due to the Earth’s magnetic field. The field has a
strength of 5.5 x 10-5 Teslas (T) to the north.
Find the speed of the proton.
q = 1.60 x 10-19 C B = Fmagnetic
B = 5.5 x 10-5 T qv
Fmagnetic = 8.8 x 10 10-19 N
v = Fmagnetic
qB
Fmagnetic = qvb SinѲ

18. Solution
v =
8.8 x 10-19 N
(1.60 x 10-19 C) (5.5 x 10-5 T)
1.0 x 10 5 m/s

19. The direction of the
magnetic force is
perpendicular to the
plane of the magnetic
field and to the
direction of the charge.
USE THE RIGHT
HAND RULE!!!

20. Current carrying wires that are placed
in a magnetic field also experience a
magnetic force.
I – CURRENT
F- FORCE
WIRE

21. The magnitude of the magnetic force can
be written in terms of the current (I)
flowing through the length of the wire (L).
Magnetic Force in a Current Carrying wire
F = BIL

22. A 10.0 m long power line carries a current of 20.0 A
perpendicular to the Earth’s magnetic field of
5.5 x 10 10-5 T.
What is the magnetic force experienced by the power
line?
I = 20.0 A
B = 5.5 x 10 10-5 T
L = 10.0 m
F = BIL
F = (5.5 x 10 10-5 T)(20.0 A)(10.0 m) = 0.011 N

23. Charges that are in motion (an electrical current)
produce magnetic fields.
Magnetic field moves
around a wire with a
current in a circular
fashion.
Which direction???

24. Right Hand Rule
1. Thumb goes in the
direction of the current.
2. Fingers wrap around wire
in the direction of the
magnetic field.

25. Arranging wire in a coil and running a current
through produces a magnetic field that is similar
to a bar magnet.

26. • A coil wound
into a tightly
packed helix.
•Produces a
uniform
magnetic field
when a charge
is applied to it.

27. 1. A particle with a positive charge of q moves with a speed v and passes
through a magnetic field B parallel with the speed v. What is the magnitude
of the magnetic force on the particle?
a) F = qvB
b) F = -qvB
c) F = 0
d) F = qvB/2
e) F = -qvB/2
2. In the figure below, a magnetic field of .01 T is applied locally to a wire
carrying a current of intensity I = 10A. What is the magnitude of the
magnetic force applied to the wire?
a) F = .3N
b) F = .4N
c) F = .5N
d) F = 1N
e) F = 3N

28.  A wire 36 m long carries a current of 22A from east to west. If the
maximum magnetic force on the wire at this point is
downward(toward Earth) and has a magnitude of 4.0 X 10-2 N, find
the magnitude and direction of the magnetic field at this location.
 Given: l = 36 m I = 22A Fmagnetic = 4.0 X 10 -2 N
 Unknown: B = ???
 Fmagnetic = B ∙ I ∙ l then B = Fmagnetic
Il
B=

29. 1. A particle with a positive charge of q moves with a speed v and passes through a magnetic field B parallel with the speed v. What is
the magnitude of the magnetic force on the particle?
a) F = qvB
b) F = -qvB
c) F = 0
d) F = qvB/2
e) F = -qvB/2
Solution: c)
The force F, on the charge q moving with a velocity v in a magnetic field b is F = q(v x B).
The magnitude of F is F = q·v·B·sinθ where θ is the angle between v and B.
In our case the v and B vectors are parallel, so sinθ = 0. In conclusion F = 0.
2. In the figure below, a magnetic field of .01 T is applied locally to a wire carrying a current of intensity I = 10A. What is the magnitude
of the magnetic force applied to the wire?
a) F = .3N
b) F = .4N
c) F = .5N
d) F = 1N
e) F = 3N
Solution: b)
The magnitude of a magnetic force applied to a current-carrying wire situated in a magnetic field is
F = I·B·l·sinθ
where:
· l is the length of the wire,
· B is the magnetic field strength
· I is the current in the wire,
· θ is the angle between the wire and the magnetic field.
In our case sinθ = 4/l so l·sinθ = 4m.
F = 10A·.01T·4m = .4N

30.  A wire 36 m long carries a current of 22A from east to
west. If the maximum magnetic force on the wire at this
point is downward(toward Earth) and has a magnitude of
4.0 X 10-2 N, find the magnitude and direction of the
magnetic field at this location.
 Given: l = 36 m I = 22A Fmagnetic = 4.0 X 10 -2 N
 Unknown: B = ???
 Fmagnetic = B ∙ I ∙ l then B = Fmagnetic
Il
B = 4.0 X 10-2 N = 5.0 X 10-5 T
(22A)(36m)