by Herman Restrepo
"Teaching High School Physics"
Physics 301
Fall 1998
Illinois State University
Carl J. Wenning, Instructor
I. UNIT OVERVIEW
A. Summary
This unit plan will cover wave phenomena, from simple mechanical wave motion to sound and finishing with the an introduction to lights wave like properties. The bulk of the lessons will be taught with an emphasis towards the concepts involved, using a minimum of mathematics and formula work. Historical and professional perspectives as well as recent developments in the area will be interlaced throughout the unit. This unit will fit well in a junior level physics call, whose students have completed math courses up to algebra. The text used will be Paul Hewitt's Conceptual Physics.
B. Goals
There are three different types of broad goals which will guide and shape this unit; content knowledge goals, process skills goals, and scientific dispositions goals. As far as content, students will be able to describe wave motion qualitatively as well as define the pertinent terms associated with wave motion. Students will also be able to correctly describe sound and light as wave phenomena, with properties of interference, Doppler shift, energy transmission, etc. These goals reflect the recommendations of the National Science Education Standards' content standard B and Project 2061, the Physical Setting: goal F.
The process skills which students will attain include, the ability to set up and carry out a laboratory experience which deals with the investigation of wave properties, be it mechanical waves, sound waves, or light waves. Students will also be able to correctly carry out the resolution of mathematical problems dealing different waves and wave interactions. These goals reflect the recommendations set forth in Project 2061, under The Nature of Science, part B: Scientific Inquiry.
The student will have a better understanding of how different waves underlie much of today's technology. With this understanding students will have a greater appreciation of this physics. Students will also have a greater feeling of empowerment with this knowledge and look favorably on science and technology.
C. Rationale
1. Relevance to the student
The study of waves begins the study of modern sciences, from the discovery of the wave like properties of light up to present day quantum mechanics. Through the study of waves, sound, and light students will gain valuable knowledge of underlying principals of modern technology. Students will also learn that they can control waves using various experimental methods. This knowledge will lead into their future studies and help them to become more prepared for their futures.
2. Relevance to society
Much of today's technology is based on some of the fundamental principals and concepts to be studied in this unit. This makes of the study of these topics paramount in the sustain and furthering of our society. As we continue to explore space and the world around us we will rely on technology that uses waves of some form, from the radio and television broadcasts we use for entertainment, to the sonar, radar, and stealth technologies we use to defend our country.
3. Relevance to the scientific profession
Studying waves, sound, and light in concept, experimentally, and practically will give the student a broader sense of the science of physics. The experiences that the student has working with waves in this was will help the student to become more scientifically literate, ready to continue in the profession of science if the student so desires. As the student continues through the disciplines of science they will be aided by their understanding of this topic area, since can be applied to those alternate scientific areas.
II. CONTENT/PROCEDURES OUTLINE
A. The nature of waves
1. Mechanical waves
2. Characteristics of waves
a) Period
b) Frequency
c) Velocity
d) Amplitude
3. Amplitude and energy
4. Wave interactions
a) Reflection
b) Refraction
c) Diffraction
d) Interference
B. Sound waves
1. The sonic spectrum
2. Sound transmission
3. Speed of sound
4. Properties of sound
a) Tone
b) Pitch
c) Timbre
d) Doppler effect
e) Fundamental tones
f) Harmonics
g) Sound quality
C. Light waves
1. Light wave theory
a) Huygens' principal
b) Reflection
c) Refraction
d) Diffraction
e) Interference
f) Failures of the wave theory
III. MAJOR OBJECTIVES
A. Content Knowledge Objectives
By the end of this unit, the student will, under test conditions, be able to:
B. Process Skills Objectives
By the end of this unit, the student will, under test conditions, be able to:
C. Scientific Disposition Objectives
By the end of this unit, the student will, under test conditions, be able to:
Author a short essay, no more than 2 pages, on how waves are used in today's technology and explain whether this use is safe and necessary in our culture.
Review an article dealing with criticisms of today's technological society and write a response, no more than 2 pages, to the article.
IV. ALTERNATIVE CONCEPTIONS
In the book The Handbook of Research on Science Teaching, Dorothy Gable cites that many people have problems dealing with the concept of energy. Students come into the classroom thinking of energy as something that is burned up by the body during exercise. It is associated with movement or growth. More sophisticated students will also relate energy to such things as fire and the sun. At the highest level, students may separate energy into two categories, one which is used to describe movement, growth, and exercise and another which is used in the classroom to solve problems. It is asserted that energy should be taught with a new name, that is in class it should be called exergy, which is defined as the amount of useful energy in a system.
In his books, Physics Begins With an M and Physics Begins With another M, Mr. Jewitt reveals some other interesting alternative conceptions. One is that many students come into the classroom, and later leave it, believing that the threshold of hearing is 0 dB, which is clearly incorrect. Another is that tidal waves are caused by great disturbances in the ocean, such as an earthquake. This too is incorrect since tidal waves are caused by the gravitational pull of the sun and moon. It should be noted that usually when a student says tidal wave they mean tsunami. A third misconception that students may leave classrooms with is that water waves are transverse, because they can see floating objects "bob" up and down on the surface. Mr. Jewitt makes good explanations of why the conceptions are incorrect and there are plenty of them in his two books.
V. CLASSROOM METHODS
A. Huygens' Principal (see attached lesson plan at end of unit plan)
B. Interference (see attached lesson plan at end of unit plan
VI. DEMONSTRATIONS
A. Killer Bee
1. Vibration and sound, resonance
2. First make a "killer bee" see reference for details. The "killer bee" is a popsicle stick and rubber band contraption which will produce sound when swung around in the air. Show the "killer bee" to the students and then start swinging it. The vibration of the rubber band produces the sound. If constantly spun the "killer bee can also produce resonance. You can have the students study this simple contraption to investigate how sound is produced by the vibrating rubber band or to introduce the concept of resonance.
3. Fabish, Chuck. Try Thinking Science. Robert N. Noyce Foundation (TTS 21)
B. No Sound Through Vacuum
1. Media dependency for sound transmission
2. Place a remote control door bell inside a bell jar. Ring the bell and listen for sound. Evacuate the air from the jar and then ring the doorbell again, listen for the decrease or negation of the sound.
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-17
C. Transmission of Sound Through Wood
1. Wave transmission through media, resonance
2. Hook up a resonance box to a long wooden pole which extends out of the room. Hook the free end of the pole to a music box. Start the music box up and listen to it through the resonance box
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-15
D. Interference of sound waves
1. Interference
2. Place two speakers two meters apart and drive them at a frequency of 1000 Hz. The listener can move around the room and hear the interference pattern of sound in the room
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-26
E. Plane Waves
1. Plane wave propagation
2. Use a ripple tank and hook up a flat piece of wood to a frequency driver. This set up will produce plane waves on the surface of the water. Frequency can be varied to see the effect on wavelength
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-26
F. Single Slit
1. Huygens' Principal
2. Set up a wave table to show plane waves. Add two barriers such that a single slit is made to intercept the plane waves. A spherical wave will be produced from the opening of the slit.
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-27
G. Double Slit
1. Wave interference
2. Set up a wave table to show plane waves. Add three barriers such that a double slit is made to intercept the plane waves. Two spherical waves will be produced and will interfere with each other.
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. S-28
H. Interference Pattern of Two Slits
1. Interference of light waves
2. Set up a laser to pass through a double slit slide and project onto a wall. The wave interference pattern can be seen on the wall.
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. O-33
I. Single Slit Diffraction Pattern
1. Diffraction, Interference
2. Set up a laser to pass through a single slit slide and project onto a wall. An interference pattern will be seen on the wall. Have the students try to explain what they see.
3. Freier, G.D. 1996. A Demonstration Handbook for Physics. American Association of Physics Teachers. O-32
J. Thank You, Mr. Doppler
1. Doppler effect
2. Swing a beeping source on a long string through the air. Have the students listen to the change in the sound that they hear. Have the students compare this sound to the sound of the beeper when it is stationary.
3. Fabish, Chuck. Try Thinking Science. Robert N. Noyce Foundation (TTS 25)
K. Frequency, Wavelength and Amplitude
1. Frequency, wavelength and amplitude
2. Hook up an oscilloscope to a wave generator and a speaker. Select low frequencies in the audio spectrum so the students can hear the sounds through the speaker. Have the students view the wave on the oscilloscope. Vary the frequency and have the students note how the wavelength is affected. Next vary the amplitude of the wave and have the students note how the wave changes.
3. Kordos, Thomas. 1996. 75 Easy Physics Demonstrations. Walch. 21-22
L. Demonstrating Resonance By Shattering Glass with Sound
1. Resonance, waves carry energy
2. Hook up a speaker to a wave generator and point it at a high quality, thin goblet. First demonstrate resonance by turning the generator to a low volume and adjusting the frequency till the goblet resonates. Next alter the frequency and then turn up the volume on the speaker, the goblet should be unaffected. Now dial back to the resonant frequency and turn up the volume again, this time the goblet will shatter.
3. Berry, Donna. 1986. A Potpourri of Physics Teaching Ideas. AAPT. 242-244
VII. LABORATORY ACTIVITIES
A. Diffraction and Interference
1. Concept: The wave like nature of light
2. Procedure
a) Diffraction
Darken the Lab and set up a line source of light in a vertical position. Hold a single slit close to your eye do that it is oriented vertically (parallel to the line source) and view the line source through it from a distance of one or two meters. repeat using other single slits of different widths. Make sketches of the best diffraction patterns you observe through a narrow slit and a wide slit. Briefly describe the diffraction between the two patterns.
b) Interference
Observe the line source of light through double slits. Compare the pattern seen through pairs of slits of different spacing. Sketch your best pattern observed through very closely spaced slits and your best pattern observed through the more widely spaces slits. Observe a single slit pattern again and carefully note the similarities and differences.
Examine a double slit pattern carefully to see if color fringes are evident. Suggest an explanation for any color effects observed. Place a color filter in front of the white light source. Record the results. Change to another color. Again record the result.
Select two color filters from the end regions of the spectrum, red and blue for example, and observe the interference pattern with first one and then the other in front of the line source of light. Describe the changes you observe.
Cover half the source with the red filter and the other half with the blue filter. From the pattern you observe, estimate the ratio of the wavelength of blur light to the wavelength of red light.
c) Answer the following questions
How does the diffraction pattern through a single slit change as a slit is made narrower?
How do interference patterns compare when formed by two narrow slits very closely spaced and by two narrow slits more widely spaced?
How do the interference patterns of red light and blue light compare when formed by the same pair of slits?
3. Trinklein, Frederick E. 1990 Modern Physics: Laboratory Experiments. Holt, Rinehart and Winston. 86-87
B. Speed of Sound
1. Concept: Resonance, speed of sound
2. Procedure (see data table at end of unit plan)
a) Hold a glass tube vertically in a cylinder nearly full of water. Make a tuning fork vibrate by holding it by the shank and striking it with the tuning fork hammer. As you hold the vibrating tuning fork over the open end of the tube, find the position where resonance produces the loudest sound by moving the glass tube slowly up and down in the water of the cylinder. Then hold the glass tube firmly while another student measures the length of the tube from the top of the tube to the water surface inside the tube. This length should be recorded to the nearest thousandth of a meter. Carefully measure the internal diameter of the tube to the nearest thousandth of a meter also. Use the thermometer to measure the temperature of the air inside the tube in degrees Celsius. A second and third trial should be taken using forks of different frequencies.
b) For each fork compute the wavelength of the sound produced from the resonant length of the tube. Also calculate the wavelength from the marked frequency of the fork and the speed of sound at the temperature inside the tube. Find the difference between these two values.
c) Answer the following questions:
(1) Through what fraction of a vibration has the prong of the tuning fork moved while the sound wave traveled down to the surface and was reflected back up to the fork again?
(2) If a longer glass tube were available, would it be possible to find another position where the resonance Is produced? Explain.
3. Williams, John E. 1968. Laboratory Experiments in Physics. Holt, Rinehart and Winston. 56-57
C. Wave Properties and the Ripple Tank
1. Concepts: Wavelength, Frequency, wave velocity
2. Procedure
a) Show the students how to use the hand strobe to make a moving wave look like a standing wave. Introduce the students the ripple tank apparatus and tell them that they need to find the speed of waves in water. Let them develop the procedure from this point on. At the end of the lab have the students write out the procedure which was used as well as any data tables, graphs, and calculations which they used. Also ask the students to write a report detailing problems which were encountered in the lab and how these where resolved. Remember to bar the use of lab workbooks which may contain this experiment, or one similar to it. As an optional activity, have the students find the speed of waves in different substances, such as olive oil or heavy castor oil.
3. Restrepo, Herman D. 1998
VIII. SAFETY CONSIDERATIONS
A. Safety Responsibilities
There are three levels for responsibility of safety in the school. The first is the school's Principal. The principals responsibilities generally are associated with the physical facilities of the school. It is his/her responsibility to make sure that things like water, gas, and electricity are properly routed through and supplied to the school itself. It is also the principals responsibility to equip and keep functioning such lab safety items as fume vents, fire fighting equipment, and eye showers.
The second level of responsibility rests on the shoulders of the Science department chair. The department chair must keep all the faculty under him/her aware of any and all safety concerns in the lab classrooms. Also, the department chair must present any safety concerns to the principal, so that the principal can make necessary changes. The department chair is also responsible for lab equipment and chemicals.
The third level of responsibility is in the hands of the teacher. The teacher is responsible for the immediate safety of the students when they are in his/her classroom. The teacher should inform the class as to emergency procedures, safety concerns specific to lab exercises and demonstrations. The teacher must also make sure that the class carried out lab exercised in a safe fashion, and with all necessary precautions.
B. There are a few safety considerations when dealing with waves, whether they are mechanical, sound, or light waves. Since waves carry energy it is possible to do harm to a student or the classroom, controlling the waves should be a priority for the instructor. There will also be the use of lasers in this unit and these lasers must be handles properly, either by the instructor or under the direct supervision of the instructor. Mechanical waves may be driven by a motor or vibrator and these could cause injury if mishandled.
C. Laser demonstrations need to be handled by the instructor so that the laser is not used improperly. The laser must be kept above eye level, or the area in front of the laser must be kept clear of people. In Doppler demonstrations where a sound source is being spun through the air, the instructor must be sure not to allow the traveling source to strike anything. When working with speakers and amplifiers the instructor must make sure that the sound emitted does not reach the pain threshold of humans. When working with a strobe lamp the instructor must be aware of any students who have a history of epilepsy. In the event of an injury the instructor must immediately contact the schools office and request assistance from the school nurse and try to minimize the personal injury of the student by keeping the rest of the student body calm and away from the accident area.
IX. SPECIAL STUDENT NEEDS
A. Student with disability: Paraplegia
Paraplegia is the lack of motor function in two limbs, generally this is manifested in the loss of use of both legs. This disability can be a natural occurrence or can result from an accident which caused bodily harm. In either case the person is usually wheelchair bound.
B. Potential handicaps
A classroom is full of potential handicaps, especially in older buildings where wheelchair access was not a consideration. Leading the list of handicaps are stairs, since they cannot be safely traversed on a wheelchair. Desk heights which are too high would also be a handicap to this student. Desk placement with restricted width would also be a handicap.
C. Accommodations
The first step in making accommodations would be to talk to the student and find out what he/she would like to have modified. Aside from this I would definitely make sure that there was full access to my room for that student. I would also be sure to arrange the desk layout (if possible) so that the student could access most, if not all, areas of the classroom. I would have to make sure that this student could work in groups with other students by having an alternate desk set up for that group.
D. Gifted student activity
An example enrichment activity I could provide for a gifted student would consist of a research paper tied into a laboratory experience. I would develop a list of topics associated with light or sound which the student could choose from. The student would then do research to find out about an experiment dealing with the topic. The student could then write a report, or prepare a presentation about the experiment and the experimenter. Finally, the student would try to recreate the experiment (if possible) to carryout and then modify. In the end the student would again have to write a report or make a presentation on the modified experiment.
E. ESL student
I would work with an ESL student by finding texts or resources which he/she could understand. I would check to see if there was a special ESL teacher in the building who could help me gather and choose proper resources for the student. I would have to make a set of minutes for each class day for the student as well, so that he/she could review what was said in class at his/her own speed.
X. STUDENT ASSESSMENT
A. Process skills assessment
1. The following set of data was recovered from a listening post buried deep within the crust of the planet Mars.
a. 1000 Hz 0.533 m
b. 2000 Hz 0.270 m
c. 500 Hz 1.062 m
d. 4000 Hz 0.133 m
e. 10000 Hz 0.053 m
a. What does this data represent?
b. Is there a relationship between the two numbers in each data set? If so, what is this relationship?
c. Create a data table for the data from Mars, remember to include proper headings and units.
d. Make a graph using this data, then find the slop and report your findings about this data and what you can infer from it.
B. Scientific disposition assessment
1. Write a five paragraph essay on one of the following topics:
a. Technology has shaped the way that the world communicates, travels, spends leisure time, and wages war. Has technology helped mankind improve life on Earth? Defend your answer.
b. If possible, would you change the curriculum of high schools to exclude upper level sciences; since these courses could be taught in college where not everyone must take them? Defend your answer.
C. Learning styles
1. Solve the following problem:
A wave with a frequency of 60 Hz has a velocity of 12 m/s in a particular medium. (a) What is the wavelength? (b) If the wave is transmitted into another medium, in which it is propagated at a speed of 20 m/s, by how much will the traveling wave change? (The frequency remains the same)
2. Write a short essay describing how waves change when traveling through different media. For example, going from water into oil and then from oil into kerosene. (Oil has a higher density than water. Water has a higher density than kerosene.)
3. A wave train passes through three different substances, diagram how the wave train changes when it cross over a boundary between two of the substances. First going from the medium density substance to the high density substance. Then from the high density substance to the low density substance.
XI. CONGRUENCE WITH STATE AND NATIONAL GOALS
A. Illinois State Goals
Illinois State Learning Goal 12 states: "Understand the fundamental concepts, principals and interconnections of the life, physical and earth/space sciences." This unit introduces many new concepts to the students, such as wave propagation, interference, energy carried by waves, and Doppler shifting. These concepts not only apply to physics but also to earth and space sciences. Waves are also used in medicine for such things as ultrasound mapping. This unit also addresses the properties of light and sound which correspond to section C of State Goal 12, which urges that students should be able to know and apply concepts such as these. The class will also be looking at the connection between wave theory and modern technology, theoretical and experimental inquiry of wave phenomena, and how to carry out these experiments in the laboratory setting.
B. National Science Education Standards
Some of the topics we cover in this unit will be dealing with how energy is carried, and can be transferred by waves, be they mechanical, sound, or light waves. This is in agreement with the goals set forth under the heading "Interactions of Energy and Matter" in Content Standard B of the National Science Education Standards. We will also be making use of many inquiry and cooperative learning lessons throughout this unit, especially when introducing new topics to the students. This is also discussed in the National Science Education Standards, under the Teaching Standards section. Specifically standard A which reads "Teachers of science plan an inquiry-based science program for their students" and standard E which reads "Teachers of science develop communities of science learners that reflect the rigor of scientific inquiry and the attitudes and social values conductive to science learning".
C. Project 2061's Benchmarks for Scientific Literacy
This unit also closely mirrors some of the standards recommended in Project 2061's Benchmarks for Scientific Literacy. For example, our lessons on the Doppler effect coincide with Physical Setting standard, part F, Motion, which in part states that "observed wavelength of a wave depends upon the relative motion of the source and the observer." Our work on interference, reflection, refraction, and diffusion coincide with this same standard which late states "Waves can superimpose on one another, bend around corners, reflect off surfaces, be absorbed my materials they enter and change direction when entering a new material." At the end of the unit we will be discussing how the dual nature of light, particulate and wave like, changed the direction of physics. This is addressed in the Nature of Science, part A, The Scientific World View standard which states in part that "From time to time major shifts occur in the scientific view of how the world works." Finally, by introducing concepts in inquiry based lessons and cooperative group labs part B of this same standard is met. This standard states that "Investigations are conducted for different reasons, including to explore new phenomena, to check previous results, to test how well a theory predicts, and to compare different theories."
XII. PHILOSOPHY OF TEACHING STATEMENT
My personal educational philosophy is that it is my job to create relevant learning experiences for my students. This means that I will nor be adhering to a single given textbook throughout the course of this unit. I will also vary the learning environment for the students, switching modes of content delivery to suit the various learning styles in the classroom. I will also vary my means of assessment techniques so that I can best judge whether or not the students understand the concepts and procedures presented in class. This style will help to keep limits from impeding my students, both in instruction and assessment. I leave the responsibility of learning to the student, though I will do my best to help them learn. From this philosophy stems several of my belief statements:
All students must have the same opportunities to learn, regardless of their ability to take advantage of these opportunities
The teacher has the responsibility of creating the opportunities for students to learn, but not the responsibility of making the students learn.
The teacher must vary the types of opportunities which the students can take, as well as the environment in which the opportunities are presented.
Students have a right to have a limited voice in the choice of environment and content delivery when participating in a class. This will give the students ownership of their learning, adding to their internal motivation in class.
The teacher must maintain an environment in which the student can learn, using strict rules which are handled in a fair and equitable fashion.
XIII. REFERENCES
A. Fabish, Chuck. Try Thinking Science. Robert N. Noyce Foundation.
B. Williams, John E. 1968. Laboratory Experiments in Physics. New York, NY: Holt, Rinehart and Winston.
C. Trinklein, Frederick E. 1990 Modern Physics: Laboratory Experiments. New York, NY: Holt, Rinehart and Winston.
D. Freier, G.D. 1996. A Demonstration Handbook for Physics. College Park MD: American Association of Physics Teachers.
E. Serway, Raymond A. 1992. Physics for Scientists and Engineers. Pittsburgh, PA: Saunders College Publishing.
F. American Association for the Advancement of Science. 1993. Project 2061: Benchmarks for Scientific Literacy. New York, NY: Oxford University Press
G. Arons, A.B. 1990. A Guide to Introductory Physics Teaching. New York, NY: John B Wiley and Sons.
H. Gable, Dorothy L. 1994. The Handbook of Research on Science Teaching and Learning. New York, NY: MacMillian.
I. National Research Council. 1996. National Science Education Standards. Washington, DC: National Academy Press
J. Safety in the Secondary Science Classroom. 1978. Washington, DC: National Science Teachers Association.
K. Jewitt, J. W. 1994. Physics Begins With an M...Mysteries, Magic, and Myth. Boston, MA: Allyn and Bacon.
L. Jewitt, J. W. 1996. Physics Begins With another M...Mysteries, Magic, Myth and Modern Physics. Boston, MA: Allyn and Bacon.
M. Trinklein, F. E. 1990. Modern Physics. New York, NY: Holt, Rinehart and Winston
N. Kordos, Thomas. 1996. 75 Easy Physics Demonstrations. New York, NY: Walch
O. Berry, Donna. 1986. A Potpourri of Physics Teaching Ideas. College
Park MD: American Association of Physics Teachers.