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Meaningful Applications Of Physical Sciences
Dr. Michael H. Suckley
Mr. Paul A. Klozik
Email: [email protected]
MAGNETISM
I. Teacher Notes
A. Naïve Ideas
B. Workshop Objectives
II. Building A Model of Magnetism
III. Applying Magnetic Principles
MAGNETISM
II. Building A Model of Magnetism
A. Magnetic Nature of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Magnetic Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
B. Law of Magnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Law of Magnetism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
C. Magnetic Fields
Mapping Magnetic Fields of A Magnet . . . . . . . . . . . . . . . . . . . . 5
Mapping Magnetic Fields of Like and Unlike Magnetic Poles . . 5
Mapping Magnetic Fields Using Iron Filings . . . . . . . . . . . . . . . 6
Analyzing Magnetic Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
D. Structure Of Magnets . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
The Tube And Iron Filings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Applying The Model Of Magnetism To A Iron Wire . . . . . . . . . 9
E. Measuring The Force of A Magnetic Field. . . . . . . . . . . . . . . . . . . .10
MAGNETISM
III. Applying Magnetic Principles
A. The Earth's Magnetic Field
Determining Direction and The Earth’s Magnetic Field . . . . . . . . . . 11
Investigating the Earth’s Magnetic Field . . . . . . . . . . . . . . . . . . . . . . 11
B. Relationship Between Electricity and Magnetism . . . . . . . . . . . . . . . 12
The Affect of Electricity Upon The Production of Magnetism . . . 12
The Affect of Magnetism Upon The Production of Electricity . . . .13
C. Determining The Strength of An Electromagnet . . . . . . . . . . . . . . . . .14
D. Magnetism and Electric Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Constructing An Electric Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
We Had A Great Time
Workshop Objectives
1. Determine which materials are magnetic and which are not.
2. Determine the Law of Magnetism.
3. Determine the geometry, or shape, of the magnetic field surrounding
a magnet or a combination of magnets.
4. Describe the structure of a magnet.
5. Describe the Earth’s magnetic field.
6. Describe how the magnetic force of a magnetic changes with
distance.
7. Describe the influence of electricity on the production of magnetism.
8. Describe the influence of magnetism on the production of electricity.
9. Describe the construction of a motor applying the magnetic principles
learned in this unit.
8
Naive Ideas
1. All metals are attracted to a magnet.
2. All silver colored items are attracted to a magnet.
3. All magnets are made of iron.
4. The magnetic and geographic poles of the earth are located at the same
place.
5. The magnetic pole of the earth in the northern hemisphere is a north
pole, and the magnetic pole in the southern hemisphere is a south pole.
6. Larger magnets are stronger than smaller magnets.
7. Magnetic poles are always located at the ends of the magnet.
6
Magnetic Classification Materials
Diamagnetic materials –
these are materials that are not attracted to a magnet
and are sometimes referred to as nonmagnetic
materials.
Paramagnetic materials –
these materials are weakly attracted to a magnet,
however, the attraction may be so weak it is not even
noticeable. These are commonly referred to as
nonmagnetic materials also.
Ferromagnetic materials – these are materials such as magnetite, those do-dads
and souvenirs we prominently display on our
refrigerator doors, and any other materials that can be
used to produce a “permanent magnet”. These are also
the kinds of materials that are most strongly attracted
to a permanent magnet.
2
Which Materials are Magnetic?
Indicate by placing an Y or N for any magnetic materials found.
Material
Magnetic (Y/N)
Material
1. Lead
10. Wood
2. Steel
11. Rubber
3. Plastic Shot
12. Candy Topping
4. Colored Glass
13. Zinc
5. Aluminum
14. Gravel
6. Cobalt
15. Silver
7. Copper
16. Magnesium
8. Nickel
17. Tin
9. Brass
Magnetic (Y/N)
The Law of Magnetism
1. Obtain two unmarked magnets and one marked/reference magnet.
2. Adjust one of the unmarked magnets so that it is attracted to the S marked end of the
reference magnet. Place a mark on the unmarked magnet indicating the attracted end.
3. Adjust the second unmarked magnet so that it is also attracted to the S marked end of
the reference magnet; place a mark on the second unmarked magnet indicating the
attracted end.
4. You have now identified (and marked) the ends of each ‘unmarked’ magnet. The ends
that are now marked both behave the same with respect to the reference magnet. This
means that the marked ends are similar or like poles.
5. Bring these two recently marked ends together. Describe what happens when two like
poles are brought together.
6. Bring one marked end and one unmarked (unlike) end together. Describe what
happens when two unlike poles are brought together.
2
Like Poles
Unlike Poles
Repel
Attract
Mapping Magnetic Fields

M
A
G
N
E
T

M
A
G
N
E
T




M
A
G
N
E
T





Figure 3
2
Mapping Magnetic Fields
2
1
Mapping Magnetic Fields
0
Mapping Magnetic Fields
Single
Magnet
Unlike
Poles
Like
Poles
C2 – Matching Magnetic Fields
Section 1 - Single Magnet
N
N
N
N
N
S
S
S
S
S
A
B
C
D
E
CORRECT
2
C2 – Matching Magnetic Fields
Section 2 – Unlike Poles
N
N
N
N
N
S
S
S
S
S
S
N
N
N
N
N
SS
S
S
S
S
A
B
C
D
E
CORRECT
1
C2 – Matching Magnetic Fields
Section 2 – Like Poles
N
N
N
N
N
S
S
S
S
S
S
S
A
B
C
D
CORRECT
E
0
Viewing Magnetic Fields
Using Iron Filings
Clear Plastic Lid
Magnets
Iron Filings
1
Viewing Magnetic Fields
Using Iron Filings
Single
2
Unlike Poles
Like Poles
0
The Structure of Magnets
Random
Nucleus
Iron
Figure 6
Unmagnetized
Partially Magnetized
Magnetized
Aligned
The Tube and Iron Filing
Figure 9
Applying The Magnetic Model
To a Iron Wire (Paperclip)
Unmagnetized
Figure 10
Magnetized
Figure 11
Measuring The Strength Of Energy
The Inverse Square Law
Object
Strength = 1/4
Strength = 1
One Distance Unit
Two Distance Units
Strength = 1/9
Three Distance Units
1. Hold the laser 1 meter as indicated in the table and shine on a flat surface. You will notice squares
reflecting on the surface. Select one of the squares and draw it on the surface.
2. Hold the laser 2 meters from the surface. Align the same square with one side and bottom. Determine
the number of original squares it would take to fill the larger square.
3. Hold the laser 3 meters from the surface. Align the same square with one side and bottom. Determine
the number of original squares it would take to fill the larger square.
Distance
12
1-Meter
2-Meters 3-Meters
Number of Squares
1
4
9
Distance Squared (D)
1
1
4
1/4
9
1/9
1/D2 ∞ intensity
Floating Magnet
1
Creating A Compass
The first step is to turn the
needle into a magnet. The
easiest way to do this is with
another magnet -- stroke the
magnet along the needle 10 or
20 times.
Place your float in the middle of your dish of water. The "float on water" technique
is an easy way to create a nearly frictionless bearing. Center your magnetic needle
on the float. It very slowly will point toward north. You have created a compass!
0
Figure 15
The Earth's Magnetic Field
N
S
S
N
4
1
The Earth's Magnetic Field
Geographic
North Pole
Magnetic
South Pole
Earth
Magnetic
North Pole
Geographic
South Pole
0
Affect of Electricity on Magnetism Fields
3
Observing Magnetism
Associated With Flowing Electrons
2
Investigating the Magnetic Field
Associated With Flowing Electrons
1
Describing the Magnetic Field Associated
With Current Flowing in a Wire
N
Black
Red
W
E
Wire Below Compass
S
N
Black
Red
E
W
S
5
Wire Above Compass
End View Of Wire
0
Producing and Detecting Electricity
Coil of Wire
current detector
Connecting Wire
Magnet
Number of Wire Wraps
Approx 100
Current Detector
Movement
Approx 300
8
Hand Generator
7
Motor Generator
6
Flashing Wheels
5
Forever Flashlight
4
Radio Speakers Convert Electrical to Mechanical Energy
A speaker takes the electrical
signal and translates it into
physical vibrations to create
sound waves. Speakers do this
by rapidly vibrating a flexible
diaphragm or cone. The cone is
connected to the voice coil.
When electricity passes through
the coil a magnetic field is
produced which interacts with
the magnetic field of the
magnetic. This causes the coil
and cone to move producing
sound.
3
Radio Speaker/ Cheepie Speaker
Idea from: Al Guenther
2
Musical Motor
Idea from: Al Guenther
1
Signals Through Space
Idea from: Al Guenther
0
Determining The Strength Of An Electromagnet
Iron
Core
Wire
Connect to
Power Source
Staples
Trial
Turns
1
25
2
50
3
75
4
100
Observation
Compass (Yes or No)
Number of Staples
Compass (Yes or No)
Number of Staples
Compass (Yes or No)
Number of Staples
Compass (Yes or No)
Number of Staples
Figure 21
Iron
Aluminum
Wood
Motors and Generators
Simulation
Armature
Commutator
Axle
Brushes
North
South
Current
Magnet
Figure 7
5
Student Motor
Large Paper Clips
Magnet
Armature
Rubber Band
4
3
2
1
The Finished Motor
0
We Had A Great Time