Download How Do Magnets Affect One Another?

Magnetism Outline
Prepared for BW Physics
by
Dick Heckathorn
16 April 2 K + 12
1
Table of Contents
1A1
1A2
1B1
1B2
1C1
1E1
1E3
1C1
1D2
How Do Magnets Affect One Another?
What metals do magnets attract?
Exploring Magnets
How can strength of different magnets be
compared?
Where is a magnet the strongest?
How Do Magnets Affect One Another?
Where are the poles?
Which way is north?
Which end of the magnet points north?
2
Table of Contents
1F1 The magnetic Poles of the earth
1F2 A compass needle points toward magnetic north
1G1 What happens when magnets are broken or cut?
1G2 What’s wrong with these pieces of magnets?
1H1 How are magnet particles arranged?
1H2 Magnetic and non-magnetic materials
1H3 How can you make a magnet?
1I1 How can you ‘unmake’ a magnet?
1D2 Which is the Magnet?
3
Learning Station 1
How Do Magnets Affect
One Another?
1A1
page 13
4
1A1 Learning Station 1
1. Pick objects of your choice.
2. How are all of the objects which are
attracted to the magnet alike?
3. What can you infer about the kind of
objects which are attracted to a
magnet?
5
All
Learning Station 2
What metals do magnets
attract?
1A2
page 15
6
Station
1A2 Learning Station 2
paper clip, jar lid, scissors, iron nail,
stainless steel spoon, metal bolt,
hammer
aluminum pie plate, copper penny, lead
pipe, brass key, aluminum foil
7
Station
1A2 Learning Station 2
1. In bag A what do all objects have in
common?
2. What conclusions can come to?
3. In bag B what do all objects have in
common?
8
Station
Learning Station 3
Exploring Magnets
1B1
page 17
9
Station
1B1 Learning Station 3
1. Using a paper clip, which objects are
magnets and which are not?
10
Station
1B2 Learning Station 4
2. Stick one end of each magnet into a
pile of paper clips on the table. See
how many clips you can pick up with
the magnet. Describe the results.
3. Try testing the strength of the magnets
by placing a paper clip on the end of
the magnet and making a chain by
touching another paper clip on the
bottom of the first.
12
Station
1B2 Learning Station 4
4. Test the magnet for the distance
through which it will attract a paper
clip.
13
Station
Learning Station 6
How Do Magnets Affect One
Another?
1E1
page 27
16
Station
1E1 Learning Station 6
1.
What did you learn?
17
Station
1E1 Learning Station 6
Prediction
How would you use
a bar magnet
with the N and S poles marked
to identify
a bar magnet
that is not marked?
18
Station
Learning Station 7
Where are the poles?
1E3
page 33
19
Station
1E3 Learning Station 7
1. Discuss why the
magnets behave as they
do as you manipulate
them one above the
other.
20
Station
Learning Station 8
Which way is north?
1D1
page 25
21
Station
1D1 Learning Center 8
1. Which way is a magnet orientated when it
stops rotation.
2. Suppose you have a bar magnet with the N
and S rubbed off.
How can you tell which end is the N-Pole
and which is the S-Pole?
22
Station
1D2 Learning Center 9
1. Magnets are magnets and behave in a
similar manner.
2. Thus, what explanation might one give
for the peculiar behavior?
24
Station
Learning Station 10
The magnetic Poles of the
earth
1F1
page 35
25
Discuss
1F1 Learning Center 10
26
Discuss
Learning Station 11
A compass needle points
toward magnetic north
1F2
page 37
27
Discuss
1F2 Learning Center 11
28
Station
1F2 Learning Center 11
THE MAGNETIC POLES OF THE EARTH
p 36
29
Discuss
April 26
30
Learning Station 16
How can you make a
magnet?
1H3
page 49
31
Station
1H3 Learning Center 16
WHAT HAPPENS WHEN MAGNETS ARE BROKEN OR CUT?
32
Station
1G1 Learning Station 12
1. Rubbing wire over large magnet
causes the wire to _________ .
2. Any way to test your idea?
3. Your results?
33
Demo
Learning Station 12
What happens when
magnets are broken or cut?
1G1
page 39
34
Demo
1G1 Learning Station 12
1. Bring the wire rubbed on the magnet
near a compass.
2. Your results?
3. Cut wire into two pieces.
4. Compass says?
35
Demo
Learning Station 13
What’s wrong with these
pieces of magnets?
1G2
page 41
36
Discuss
1G2 Learning Station 13
When an iron magnet is broken into
pieces, all new pieces of the magnet will
retain their polarity.
37
Discuss
Learning Station 15
Magnetic and non-magnetic
materials
1H2
page 47
40
1H2 Learning Station 15
41
Learning Station 17
How can you ‘unmake’ a
magnet?
1I1
page 51
43
Demo
Learning Station 17
1. What does the manual suggest as a
way to do it?
2. Demonstrate demagnetizer
3. Demonstrate magnetizer.
44
Demo
Learning Center 18
Which Is the Magnet?
1I2
page 65
45
Station
1I2 Learning Center 18
46
Station
1I2 Learning Center 18
47
Station
How Can You Study a
Magnetic Field? 19
2A2
page 57
48
Making A ‘Iron Filings’ Holder
1.
2.
3.
4.
Fold the piece of clear plastic in half.
Using scotch tape, seal two of the
three sides.
Have 1/8 teaspoon of steel shot put
into the pouch.
Seal the 3rd side with tape.
49
Do
1.
Place the magnet on the table.
2.
Shake the plastic until the spheres
are spread out.
3.
Place the plastic with spheres on top
of the magnet.
50
Do
Tap the plastic sheet.
a.
What happens to the steel spheres as
you tap the plastic?
b. Describe how the steel spheres are
scattered in the plastic?
51
Do
3.
Sketch your observations of the steel
spheres.
Be sure to outline the magnet and
label the N and S end.
52
Explanation
The pattern is produced by an invisible
pattern of magnetic force around the
magnet.
The space in which magnetism exerts a
force is called a magnetic field.
53
Explanation
The pattern that we see with the steel
spheres are called lines of force.
54
Do
4. Describe the pattern produced by the
steel spheres.
Where are the greatest and least
concentrations of spheres?
What does this represent?
55
Do
5. Place a magnet on top of a piece of
paper and then outline its position.
Push a paper clip from several
directions towards the magnet.
Mark the spot on the paper where the
attraction first occurs.
56
Question
6. How does the pattern of the spheres
correspond to the distance at which
the paperclip is attracted to the
magnet?
57
Question
7. Why doesn’t the magnet need to touch
a magnetic object to attract it?
58
Question
8. How can a magnet attract a paperclip
without touching it?
59
Conclusion
9. Based on your observations, which is
the strongest part of the magnet?
Explain.
60
The Magnetic Field Around
a Bar Magnet 20
2A3D
page 63
61
2A3 Magnetic Field Around a Bar Magnet p 63
62
What is the extent of a
magnet’s force? 21
2A1
page 67
63
2A1
1. What was the maximum number of
pages between magnet and paper
clip?
64
How can you plot a
magnetic field? 22
2B1
page 71
65
2B1
A magnetic field surrounds any magnet.
The direction of the magnetic field is
defined as the direction of the force on a
north pole (of a magnet) placed in the
field.
66
Magnetic Lines of Force 23
2B2
page 75
67
2B2
68
The Magnetic Field About
Two Magnets 24
2B4
page 77
69
Do
1. Lay 2 bar magnets on a flat surface 4cm apart.
70
Do
2. Place the plexiglas with steel spheres
on top of the magnets.
71
Do
4. Tap the plastic gently.
72
Do
5. Draw the resulting pattern.
73
The Magnetic Field Between
Like Poles
74
Prediction
6. What do you think will happen if you
repeat the experiment but with the
two magnets farther apart?
Try it and then draw your
observations.
75
Prediction
7. What do you think will happen if you
did the same experiment, but this
time, place the North and South Poles
of the two magnets 4-cm apart?
76
Prediction
8. Test your prediction.
77
Do
9. Draw your observations.
78
The Magnetic Field Between
Unlike Poles
79
Conclusion
10. What do you conclude about the
pattern made by the steel spheres
when:
a. when like poles are near each
other?
b. when unlike poles are near each
other?
80
Show 3-D models
81
The Magnetic Field About
Two Magnets 25
2B5
page 87
82
2B5
The magnetic field
between unlike poles
The magnetic field
between like poles
83
2B5
Like magnetic poles repel.
Unlike magnetic poles attract.
84
Is it only temporary?
2D1
page 91
85
Final Day
89
Demo: How Are Magnetism
And Electricity Related?
3A1
page 97
90
1 6-volt battery
30 cm length of insulated copper wire,
stripped 1 cm at ends and 3 cm at
center
iron filings, fine
sheet of paper
long wire, green power source, compass
91
Set Up
1. Place the plastic with iron filings on
the table.
2. Connect the ends of a copper wire to
the terminals of a battery.
3. Tap the plastic with your finger.
92
Do
4. Observe and record what happens.
5. Predict what would happen of the wire
is disconnected from the battery.
6. Disconnect the wire from the battery.
93
Do
7. Repeat using paper instead of the steel
spheres.
8. Compare results.
94
Infer
8. What can you infer about the
relationship between electricity and
magnetism?
95
Oersted’s Serpendipity
3A2D
page 101
96
Information
In the early 1700’s, lightning was
observed to change the direction of
compass needles.
Could it be that there was a relation
between electricity and magnetism?
97
Do
Lay the current carrying wire on top of a
compass. Throw switch.
What do you observe?
(This Oersted did absent-mindedly.)
98
Do
Move the compass at various position
relative to the wire and/or move the wire
relative to the compass.
What do you observe?
99
Observations
A current carrying wire will cause a
magnet needle to turn.
The magnetic field above the wire and
beneath the wire are opposite in direction.
100
Conclusion
A current-carrying wire is encircled by a
magnetic field
The magnetic field above the wire and
beneath the wire are opposite in direction.
101
Magnetic Field Surrounding
A Current Carrying Wire.
3A3D
page 103
102
2A3D
103
104
Direction Of Magnetic Field
Surrounding A
Current-Carrying Wire
3A4D
page 107
105
106
Magnetic Field About A Loop
Of Current Carrying Wire
3A6D
page 109
107
108
Magnetic Field About A Coil
Of Current Carrying Wire
3A7D
page 111
109
110
111
How Does An Electromagnet Work?
3B1
page 113
112
113
How is a magnet used to
detect electricity?
3B5
page 117
114
115
How can a magnet produce
electricity?
3C1
page 119
116
117
The Electric Wire Generator
3C2D
page 121
118
119
Force on a Wire in B Field
Demo
120
Large Motor
Demo
121
What makes a motor work?
(Making a Motor)
3D2
page 123
122
123
The Motor Generator.
3D3
page 127
124
That’s all there is folks!
125
Demonstration #1
Move a wire
through the jaws
of a
horseshoe magnet.
Results?
Large magnet – wire – Galvanometer
126
Demonstration #2
Plunge
a bar magnet
into and out of
the core of a coil.
Bar magnet – coil – wire – Galvanometer
127
Demonstration #3
theto
switch.
What Close
happens
the meter?
The two
wires are
not connected.
Anything
surprising?
Green or large power source – iron ring or my coils - wire – Galvanometer
128
Demonstration #3
Open the switch.
What happens to the meter?
Green or large power source – iron ring or my coils - wire – Galvanometer
129
Demonstration #3
theto
switch.
What Close
happens
the meter?
The two
wires are
not connected.
Anything
surprising?
Green or large power source – iron ring or my coils - wire – Galvanometer
130
Demonstration #3
Open the switch.
What happens to the meter?
Green or large power source – iron ring or my coils - wire – Galvanometer
131
Demo - Coil
1.
Used as Magnetizer
132
Demo - Coil
2.
Two Rings – Adjust Height
133
Demo - Coil
3.
Induced Voltage
134
Demo - Coil
4.
Various Size Coils
135
Demo - Coil
5.
Bulb connected to coils
136
Demo - Coil
6.
Radio Transmission
137
Demo - Coil
7.
Magnetic Braking
138
Demo - Coil
8.
Dropping Magnet
139
Demo - Coil
9.
Dropping Copper Tube
140
Demo - Coil
10. Ball Magnet
141