meaningful applications of physical sciences dr. michael h. suckley mr. paul a. klozik email:...

Meaningful Applications Of Physical Sciences

Dr. Michael H. Suckley

Mr. Paul A. Klozik

Email: MAP@ScienceScene.com

MAGNETISM

I. Teacher Notes A. Naïve Ideas

B. Workshop Objectives

II. Building A Model of Magnetism

III. Applying Magnetic Principles

MAGNETISMII. 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 Magnetic (Y/N)

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      

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.

Like Poles

Repel AttractUnlike Poles

2

Mapping Magnetic Fields

MAGNET

MAGNET

MAGNET

Figure 3

2

Mapping Magnetic Fields

12

Mapping Magnetic Fields

0

Mapping Magnetic Fields

SingleMagnet

Unlike Poles

Like Poles

C2 – Matching Magnetic Fields

A B C D E CORRECT

Section 1 - Single Magnet

N

S

N

S

N

S

N

S

N

S

2

C2 – Matching Magnetic Fields

Section 2 – Unlike Poles

S

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

A B C D E CORRECT

1

C2 – Matching Magnetic Fields

Section 2 – Like Poles

N

S

N

S

N

S

N

S

S

S

N

S

A B C D E CORRECT

0

Viewing Magnetic FieldsUsing Iron Filings

Clear Plastic Lid Magnets Iron Filings

1

Viewing Magnetic FieldsUsing Iron Filings

Single

0

Unlike Poles Like Poles

2

The Structure of Magnets

Random Aligned

Unmagnetized

Partially Magnetized

Magnetized

Nucleus

IronFigure 6

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 EnergyThe Inverse Square Law

One Distance Unit Two Distance Units Three Distance Units

Object Strength = 1 Strength = 1/4 Strength = 1/9

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.

1/91/411/D2 ∞ intensity

941Distance Squared (D)

941Number of Squares

3-Meters2-Meters1-MeterDistance

12

Floating Magnet

1

 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!  

Creating A Compass

0

Figure 15

The Earth's Magnetic Field

N

S

N

S

14

The Earth's Magnetic Field

0

Magnetic North Pole

Earth

Geographic South Pole

Magnetic South Pole

Geographic North Pole

Affect of Electricity on Magnetism Fields

3

Observing Magnetism Associated With Flowing Electrons

2

Investigating the Magnetic FieldAssociated With Flowing Electrons

1

Describing the Magnetic Field Associated With Current Flowing in a Wire

End View Of Wire

N

S

W EBlack Red

Wire Below Compass

N

S

Black Red

Wire Above CompassW E

0

5

Producing and Detecting Electricity

Number of Wire Wraps

Approx 100 Approx 300

Current DetectorMovement

current detector Coil of Wire

Connecting Wire

Magnet

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

2

Idea from: Al Guenther

Musical Motor

1

Idea from: Al Guenther

Signals Through Space

0

Idea from: Al Guenther

Determining The Strength Of An Electromagnet

Trial Turns Observation Iron Aluminum Wood

1 25Compass (Yes or No)                  

Number of Staples                  

2 50Compass (Yes or No)                  

Number of Staples                  

3 75Compass (Yes or No)                  

Number of Staples                  

4 100Compass (Yes or No)                  

Number of Staples                  

Iron Core Wire

Connect to Power Source

Staples Figure 21

Motors and Generators

Figure 7

Magnet

Current

Armature

Commutator

BrushesAxle

North South

Simulation

5

Student Motor

Magnet

Armature

Large Paper Clips

Rubber Band

4

3

2

1

The Finished Motor

0

We Had A Great Time