GET YOUR PHYSICS ON!

Transcription

1 GET YOUR PHYSICS ON! Physics TEKS 2F & 2G Student Review Activities Developed and Written by Dan Plas and Tim Sears The University of Texas Pan American 2012

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3 TABLE OF CONTENTS STAAR Reporting Category Category 1 Force and Motion (FM) Category 2 Gravitational, Electrical, Magnetic, and Nuclear Forces (FF) Category 3 Momentum and Energy (ME) Category 4 Waves and Quantum Phenomena (WQ) Station/Title TEKS Page Numbers FM01: Velocity with Photogates 2F; 4A 3-4 FM02: Getting to Know a Force 2F; 4D 5-6 Sensor Using Hooke s Law FM03: Acceleration on a Ramp 2F; 4D 7-8 FM04: Stroboscope and Tiny Fast 2F; 2G; 7B 9-11 Pendulum FM05: Getting to Know a Motion Sensor Using a Pendulum (since this activity examines motion of a pendulum, it also relates to Category 4: Wave and Quantum Phenomena) 2F; 7B FF01: Magnetic Force on an Electron 2F; 5D Beam FF02: Getting to Know a Radiation 2G; 5H Monitor FF03: Charging by Contact 2F FF04: Multimeters and Ohm s Law 2F; 5E; 5F ME01: Getting to Know a Ballistic 2G; 6B; 6C; 6D Pendulum ME02: Potential and Kinetic Energy 2F; 6A; 6B ME03: Conservation on a Ramp 2F; 6A; 6B WQ01: Guess the Gas 2F; 7C WQ02: Converging Lenses - Find the 2F; 8E Focal Length WQ03: Resonance 2F; 8B; 8C; 8D WQ04: Line Spectra 2F; 8B WQ05: Polarized Light Waves 2F; 7C; 7D The Texas Regional Collaboratives give permission to all TRC teachers or affiliated institutions to reproduce or transmit this book in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, for the purposes of teacher professional development or student instruction. The contents of this book may be reproduced only for noncommercial purposes.

4 Acknowledgements The TRC is especially grateful to all the individuals that contributed to this project. This idea began with a breakout session presented by Tim Sears and Dan Plas of the UT Pan American Regional Science Collaborative at the TRC s Eighteenth Annual Meeting. Their station- based approach to incorporating the extensive list of equipment specified in the Physics TEKS is modeled here. Since then, many people shared in the development of this project. Their efforts and ideas deserve our sincere appreciation. They include: The Texas Education Agency who funded this project. Tim Sears, Clinical Instructor at The UTeach- Pan American Program, and Dan Plas, Assistant Professor at The University of Texas Pan American who were the authors of these lessons; Hugh Henderson, AP Physics Teacher at Plano ISD, and Paula Hitibidal, Science Education Specialist at Region 15 Education Service Center, who reviewed the lessons and shared their physics expertise; Marsha Willis, TRC Professional Development Coordinator, for overseeing the compilation of this resource; Kris Mason, Assistant to TRC Executive Director, and Mary Hobbs, Coordinator for Science Initiatives, for reviewing and editing; and Nathalie Beausoleil, TRC Documentation Specialist, for formatting and creating this collection of physics lessons.

5 Student Review Stations Exploring the Physics Equipment and Apparatus Mandated in Physics TEKS 2F & 2G Physics TEKS Specifying Equipment/Apparatus: 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90-degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; 2(G) use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as ripple tank with wave generator, wave motion rope, micrometer, caliper, radiation monitor, computer, ballistic pendulum, electroscope, inclined plane, optics bench, optics kit, pulley with table clamp, resonance tube, ring stand screen, four-inch ring, stroboscope, graduated cylinders, and ticker timer Overview Information for Teachers: The recently revised high school Physics TEKS 2F & 2G specifies a lengthy list of sometimes unfamiliar lab apparatus that students are expected to be familiar with. These activities were designed to be set up as brief exploratory stations for a high school physics classroom. The main intent of each station is to ensure that all students have been exposed to the less familiar and less common physics apparatus and equipment. Additionally, they are designed to engage students and reinforce physics Readiness Standards using the equipment. Each station activity is designed to take minutes. Teachers who use the materials in this kit are encouraged to explore the many other possible uses of the apparatus. While some of the equipment -- such as the ballistic pendulum -- is designed for a single purpose, many of the other pieces of equipment can be used in a wide variety of experiments. Much of the Vernier equipment is designed to be used in different contexts, which can be easily explored through many readily available internet sites. While there is no specific activity provided for the ballistic cart, this is a demonstration that every physics student should see, and therefore it is included with the materials. The activities are suggestions, and you are encouraged to use the equipment in other ways too. The titles of each station are organized into four groups based on Physics EOC Reporting Categories: FM (force and motion) Reporting Category 1 FF (fundamental forces) Reporting Category 2 ME (momentum and energy) Reporting Category 3 WQ (waves and quantum phenomena) Reporting Category 4 Each activity includes: Relevant equipment/apparatus (indicated in bold) and relevant science concepts from the Physics TEKS Relevant Physics End of Course Assessment Reporting Category Relevant background information for students An essential question Required materials Brief review activities and questions 1

6 Although the physics equipment and apparatus is sold from many vendors and could have purchased from a number of reputable vendors, the particular equipment in the kit was purchased by the Texas Regional Collaboratives from the following vendors. The catalog number (as of July 2012) and quantity of each item is included in the table below in case you would like to purchase additional equipment. Item Vendor Catalog # Quantity Alnico Bar Magnets Sets, 10 x 7 x 100 mm Sargent-Welch CP Alnico I Horseshoe Magnets, 30 x 35 x 10 Sargent-Welch SP Attachment Weight Set Sargent-Welch WLS Ballistic Car Science Kit WW60522M00 1 Combination Track / Optics Bench Science Kit WW01755M76 1 Demonstration Potential Kinetic Track Science Kit WW47615M00 1 Digital Multimeter Sargent-Welch WLS Digital Radiation Monitor Sargent-Welch WLS Digital Stroboscope Sargent-Welch WLS Electromagnetic Spectrum Chart Science Kit WW6577M00 1 Electrostatics Materials Kit Sargent-Welch WW68933M02 1 Equilateral Prisms, Material: Glass, Side, 25 x 50 mm Sargent-Welch WL Essential Physics Demo: Resonance Pipes Science Kit WW01808M76 1 Magnetic Deflection of an Electron Beam, Power Supply & Tube Sargent-Welch WLS Polarizing Squares Sargent-Welch CP Quantitative Analysis Spectroscope Sargent-Welch CP Solderless Breadboard Science Kit WW46384M00 1 Spectrum Tube, Argon Science Kit WW62999M55 1 Spectrum Tube, Helium Science Kit WW62999M10 1 Spectrum Tube, Hydrogen Science Kit WW62999M11 1 Spectrum Tube, Neon Science Kit WW62999M15 1 Spectrum Tubes Stand with Power Supply Science Kit WW62999M26 1 Student Ballistic Pendulum Science Kit WW01751M24 1 Vernier Dual Range Force Sensor Science Kit WW01751M56 2 Vernier Dynamics System Science Kit WW01755M75 1 Vernier LabQuest Mini Science Kit WW01811M03 3 Vernier Low-g Accelerometer Science Kit WW01751M53 1 Vernier Optics Expansion Kit Science Kit WW01807M76 1 Vernier Photogate Science Kit WW01751M62 2 Note: All diagrams and photographs were created by the authors unless otherwise indicated. 2

7 Station FM01: Velocity with Photogates Purpose The purpose of this activity is to remind you of the difference between average velocity and instantaneous velocity, and to see how both can be measured with photogates. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, Science concepts. The student knows and applies the laws governing motion in a variety of situations. 4(A) generate and interpret graphs and charts describing different types of motion, including the use of realtime technology such as motion detectors or photogates [Readiness Standard] Physics EOC Reporting Category 1: Force and Motion The student will demonstrate an understanding of the relationship of force and motion in one and two dimensions. Background Information: If an object is slowing down or speeding up, its velocity is constantly changing, but we can still talk about the average velocity of the object during a certain time. This will just be the total change in position divided by the time interval. We can also talk about an object s velocity at a certain moment in time. We call that the instantaneous velocity. If you think about it, the instantaneous velocity is very close to the average velocity during a very short time interval. So for example, if I ask you what your average speed on the highway during six hours of driving was, you have to consider all the slowing down and speeding up that took place during those six hours. But if I ask you what your average speed during a half-second was, you really didn t have much time to slow down or speed up, so it s pretty much the same as asking you how fast you were going at that moment. Essential question: How can photogates be used to find approximate values for the average velocity and instantaneous velocity of a moving object? Materials: Vernier photogates Vernier track Vernier dynamics cart LabQuest 3

8 Activities and Questions: Prop up the track at one end with book. The propped-up end should be about 5 cm higher than the lower end. In the first run, set up two photogates as shown below -- one near the top and one at the bottom. Connect both to the LabQuest and collect data in pulse mode so that you can find the average velocity as the distance between the photogates divided by the time for the object to pass from the top photogate to the bottom one. Attach the aluminum rod to the top of the cart (as shown in the photograph above) so that the photogate will detect the motion of the cart. Now release the cart from the top of the ramp and calculate the average velocity as it slid down the ramp. In the second run, use a single photogate near the bottom of the track and collect data in gate timing mode. The instantaneous velocity of the cart can be calculated as the diameter of the aluminum rod divided by the blocked-to-unblocked time as the card passes through. (The LabQuest in gate timing mode will do these calculations for you if you have entered the diameter of the aluminum rod in meters.) The velocity you measure this way is actually the average velocity during the very short time the rod is passing through, but this will be very close to the instantaneous velocity at the moment the rod begins to pass through the photogate. Which was greater, the average velocity during the whole trip or the instantaneous velocity at the bottom? Does this make sense? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 4

9 Station FM02: Getting to Know a Force Sensor Using Hooke s Law Purpose The purpose of this activity is to introduce you to (or remind you of) Hooke s Law and get you acquainted with the use of the force sensor. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; Science concepts. The student knows and applies the laws governing motion in a variety of situations. 4(D) calculate the effect of forces on objects, including the law of inertia, the relationship between force and acceleration, and the nature of force pairs between objects [Readiness Standard] Physics EOC Reporting Category 1: Force and Motion The student will demonstrate an understanding of the relationship of force and motion in one and two dimensions. Background Information: Long ago, Robert Hooke noticed that most stretchy things pull back with a force that is proportional to how much they are stretched. That s Hooke s Law: F Restoring = - k x The force is called a restoring force because the stretched object tries to restore itself back to its original shape. The negative sign is there because the object always pulls back in the opposite direction. x is the amount of stretch, and k (called the spring constant) is a number for each object that tells how stiff the object is. The larger the value of k, the harder it pulls back when you stretch it. 5

10 Essential question: How can you simply verify whether an elastic object obeys Hooke s Law? Materials: Rubber band (that is your elastic object) Force sensor LabQuest data collection device Ruler Activities and Questions: Connect the force sensor to the LabQuest and hook the rubber band onto the force sensor as shown below. Stretch the rubber band by 2 cm and record the force. Then stretch it by 4 cm, and then by 6 cm, and record the force each time. 1. Does it appear that the rubber band is obeying Hooke s Law? 2. Can you calculate k, the spring constant, for the rubber band? 3. Do you think that Hooke s Law will be valid no matter how far you stretch? Explain your answer. Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 6

11 Station FM03: Acceleration on a Ramp Purpose The purpose of this activity is to use an accelerometer to measure the acceleration of a cart on a ramp. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; Science concepts. The student knows and applies the laws governing motion in a variety of situations. 4(D) calculate the effect of forces on objects, including the law of inertia, the relationship between force and acceleration, and the nature of force pairs between objects [Readiness Standard] Physics EOC Reporting Category 1: Force and Motion The student will demonstrate an understanding of the relationship of force and motion in one and two dimensions. Background Information: You may have learned that objects falling near the surface of the earth accelerate downward at a constant rate of 9.8 m/s 2. What if the object is on a frictionless ramp? Do you think its acceleration will still be 9.8 m/s 2? Or do you think it will be greater or less than 9.8 m/s 2? Essential question: What is the acceleration of a dynamics cart as it rolls down a ramp? Materials: Vernier track and dynamics cart Vernier low-g accelerometer and LabQuest. 7

12 Activities and Questions: Prop up one end of the track so it is about 10cm higher than the other end. Attach the accelerometer to the cart and to the LabQuest as shown below. Make sure the cord will not become stretched or tangled as the cart rolls down the ramp. Start the data collection and release the cart from the top of the ramp. Read the acceleration of the cart from your LabQuest data. Was the acceleration nearly constant? Was your prediction about the value of the acceleration correct? How do you know? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 8

13 Station FM04: Stroboscope and Tiny Fast Pendulum Purpose The purpose of this activity is to learn how to use a hand-held visual stroboscope to measure time intervals. In the process, you will learn or review some basics about the period of a pendulum. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; 2(G) use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as ripple tank with wave generator, wave motion rope, micrometer, caliper, radiation monitor, computer, ballistic pendulum, electroscope, inclined plane, optics bench, optics kit, pulley with table clamp, resonance tube, ring stand screen, four-inch ring, stroboscope, graduated cylinders, and ticker timer Science concepts. The student knows the characteristics and behavior of waves. 7(B) investigate and analyze characteristics of waves, including velocity, frequency, amplitude, and wavelength, and calculate using the relationship between wavespeed, frequency, and wavelength [Readiness Standard] Physics EOC Reporting Category 1: Force and Motion The student will demonstrate an understanding of the relationship of force and motion in one and two dimensions. Background Information You will remember that a simple pendulum is just a small mass swinging back and forth from the end of a light string. The time it takes the mass to make one complete trip back and forth is called the period of the pendulum. You may also remember that the period depends on the length of the pendulum but not on the amount of mass hanging. In fact, the shorter the pendulum, the smaller the period. If the period is very small, it is a challenge to measure because the mass moves back and forth very quickly. We will try to use a stroboscope to measure the pendulum s period. 9

14 A stroboscope is simply a bright light that flashes over and over at the same rate (this is called frequency, or flashes per second). The number of flashes per second can be adjusted by the user. Imagine that you run back and forth across a dark room so that it takes you 8 seconds to travel to back and forth across the room. Imagine that when you leave the south wall (your starting point), a light flashes quickly. Then the room is completely dark until 8 seconds later when the light flashes again. To someone watching in the dark, you will appear to be motionless at the south wall since all the running back and forth happens in the dark. Every time the light flashes, you are back at your starting point on the south wall so it appears that the stroboscope has frozen your motion. Of course this trick will only work if the frequency of flashing is exactly the same as the frequency of your running back and forth. That s why stroboscopes are made to be adjustable. You can adjust the frequency until the motion is frozen. Then the frequency of the periodic motion is the same as the frequency of the stroboscope s flashing. (Caution: Is that always true? What if you adjust the stroboscope to flash 16 times a second? What would you see?) Essential question: How can I use a stroboscope to measure the frequency of a short pendulum? Materials: Thread and tape A very small mass such as a round push pin (as shown in the photograph below) A stroboscope Activities and Questions: Make a short pendulum, less than 2 cm long and attach it to a table as shown below. Practice swinging it and try to estimate its period. 10

15 Now use the stroboscope to freeze the pendulum s motion. What is the frequency shown on the stroboscope? per second. Using the fact that the period Is the reciprocal of the frequency, calculate the period: seconds How can you be sure that you are measuring the period, and not twice the period, or three times the period, etc.? Does the measurement of the length of the pendulum present any kind of dilemma? Why is this more of an issue with a very short pendulum than a longer one? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 11

16 Station FM05: Getting to Know a Motion Sensor Using a Pendulum Purpose The purpose of this activity is to remind you of the meaning of the period of a pendulum, and to see how a motion sensor (one of many types of data acquisition probes) can be used to measure the period. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; Science concepts. The student knows the characteristics and behavior of waves. 7(B) investigate and analyze characteristics of waves, including velocity, frequency, amplitude, and wavelength, and calculate using the relationship between wavespeed, frequency, and wavelength [Readiness Standard] Physics EOC Reporting Category 1: Force and Motion The student will demonstrate an understanding of the relationship of force and motion in one and two dimensions. Since this activity examines motion of a pendulum, it also relates to: Physics EOC Reporting Category 4: Waves and Quantum Phenomena The student will demonstrate an understanding of waves and quantum phenomena. Background Information A simple pendulum is made by hanging a small mass (the bob ) from a light string. Then the mass is pulled to the side and released so that it swings back and forth. The time to make one complete trip back and forth is called the period of the pendulum. An obvious way to measure the period of a pendulum would be to use a stopwatch but there are other ways (it is said that Galileo used his own pulse to time the period). We will use a more modern method that uses a motion sensor connected to a graphing calculator. 12

17 Essential question: What is a pendulum s period, and what determines the period? Materials: Motion Sensor LabQuest (alternatively, a TI graphing calculator with EasyData or similar software installed) Thread or string Tape a small fairly dense mass, such as a rubber stopper or a laboratory mass Activities and Questions: Use tape, thread, and a rubber stopper to make a simple pendulum that hangs from the table. The pendulum should hang about 6 cm above the floor. When the bob is hanging straight down, we will say it is in equilibrium position. Pull the bob about 20 centimeters to the side and release it so that it swings back and forth. It should not wobble as it swings. Using your watch, phone, or the wall clock, estimate the period of the pendulum. Now place a motion sensor on the floor about 20 cm from the equilibrium position. You will swing the pendulum so that its path is perpendicular to the line of sight of the motion sensor as shown in the following diagrams: Go to the data collection software of the graphing calculator. Set up the data collection to collect 10 seconds worth of data using a collection rate of 25 samples / second. Start the pendulum and then begin your data collection. It may take a few trials before you get clean data. 13

18 Look at your graph on the graphing calculator. How can you use the graph to determine the period of the pendulum? What period do you find? seconds How does this compare with your previous estimate? What are some limitations of this method of period measurement? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 14

19 Station FF01: Magnetic Force on an Electron Beam Purpose The purpose of this activity is to examine the effect of a magnetic field on the path of moving electrons. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets,... Science concepts. The student knows the nature of forces in the physical world. 5(D) identify examples of electric and magnetic forces in everyday life [Supporting Standard] Physics EOC Reporting Category 2: Gravitational, Electrical, Magnetic, and Nuclear Forces The student will demonstrate an understanding of gravitational, electrical, magnetic, and nuclear forces. Background Information: When an electrically charged object moves through a magnetic field, the object feels a force. The faster the object moves, the greater the force. The direction of the force is a surprise: the force is at a 90 degree angle to the direction of the magnetic field and to the direction of the motion of the object! You can use the right hand rule to predict the direction of the force. Take a look at the picture: The right hand rule: For a positive current or moving positive charge in the direction of the thumb of the right hand and the magnetic field (B) along the direction of the fingers (pointing away from palm) the force (F) on the current will be in a direction out of the palm. The direction of the force is reversed for a negative charge or current. Source: To use the right hand rule, you need to know the direction of the magnetic field produced by a magnet. Just remember that the magnetic field lines point OUT OF THE NORTH POLE of a magnet and INTO THE SOUTH POLE as shown below. 15

20 Source: And you also have to remember that electrons are negative, so they do opposite of what the right-hand-rule says! In other words, the force on the negative electron will point out of the BACK of your right hand, not the palm as shown in the picture above. Essential question: Can you predict in what direction a beam of moving electrons will bend when placed near the pole of a magnet? Materials: Bar magnet (Physics 2(F) specifies a horseshoe magnet, but a bar magnet will work) Electron Beam apparatus (cathode ray tube) Activities and Questions: Before you begin the experiment, examine the electron beam apparatus. Can you identify where the electron beam originates? With your right hand held open, point your thumb in the direction the electron beam is traveling. Remember that your fingers represent the direction of a magnetic field (there is no magnetic field yet!). Since we are looking at electrons, which are negative, the back of your hand represents the direction of the force on the electrons, so the beam should bend in that direction. Now use the north pole of the bar magnet to provide a magnetic field on the electron beam. Observe the path of the beam. Was your prediction verified? What would happen if you used the south pole of the magnet instead? Use your right hand to explain why. Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 16

21 Station FF02: Getting to Know a Radiation Monitor Purpose The purpose of this activity is to remind you of the different kinds of radiation that result when an atomic nucleus disintegrates, as well as to allow you to use a radiation monitor. Physics TEKS 2(G) use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as ripple tank with wave generator, wave motion rope, micrometer, caliper, radiation monitor, computer, ballistic pendulum, electroscope, inclined plane, optics bench, optics kit, pulley with table clamp, resonance tube, ring stand screen, four-inch ring, stroboscope, graduated cylinders, and ticker timer Science concepts. The student knows the nature of forces in the physical world. 5(H) describe evidence for and effects of the strong and weak nuclear forces in nature. Supporting Standard Physics EOC Reporting Category 2: Gravitational, Electrical, Magnetic, and Nuclear Forces The student will demonstrate an understanding of gravitational, electrical, magnetic, and nuclear forces. Background Information: The nucleus in most atoms is stable. But there are some isotopes of some of the elements that have unstable nuclei, they will eventually come apart and a little piece may break off and fly away at high velocity. This is called radioactivity, and there are three common types of radioactive radiation that leave unstable nuclei: 1. Alpha particles: These are heavy particles that contain two protons and two neutrons. Because they have a charge of +2 (can you explain why?), alpha particles interact with matter very easily, and so they can be stopped by several sheets of ordinary paper. 2. Beta particles: The weak nuclear force can suddenly convert a neutron into a proton and an electron inside a nucleus. The electron is produced with very high energy, so it flies out of the nucleus at high velocity. This high-speed electron is called a beta particle. Because it is light and has such small mass and small charge, it takes more matter to stop a beta particle than an alpha particle. Beta particles can penetrate through a thin sheet of aluminum. 3. Gamma rays: These are not particles of matter at all, but are very high energy electromagnetic radiation -- a dangerous form of invisible light. Gamma rays result when an excited nucleus relaxes into a lower energy state and emits the leftover energy as a photon of short-wavelength radiation. Gamma rays can penetrate through sheets of thin steel, and lead is often needed to stop them completely. 17

22 One of the best known elements with an unstable nucleus is uranium with atomic number 92. You probably know that uranium can be used to make a nuclear bomb or a nuclear reactor. But uranium has been used for many other purposes. Uranium oxide is a beautiful orange color, and in the 20th century, uranium oxide was sometimes used to color ceramics orange. (Why do you think this is no longer done?) One famous brand of dinner ware, Fiesta Ware, used this practice to produce their orange plates, coffee cups, saucers, etc. Uranium oxide was also used to produce a light greenish glass which is still made into beads and marbles. Essential question: What is the result when an unstable atomic nucleus decays? Materials: Vernier radiation monitor Orange Fiesta Dinnerware saucer or plate (also known as Fiestaware) or uranium glass bead Several sheets of paper Activities and Questions: Refer to these photographs to complete the activity described below. Turn on the radiation monitor and bring the Fiesta Dinnerware plate or uranium glass bead near the monitor. Does the monitor detect any radiation? The radiation monitor will produce more noise in the presence of increased radiation. Arrange the radiation monitor or uranium bead in a stable position with the plate located about 3 cm from the monitor. Begin to record, and after recording for about 20 seconds, insert a sheet of colored paper between the monitor and the plate. Do you notice any change in the radiation level detected by the monitor? Now begin to add more sheets of paper between the monitor and the plate until you notice a change. Record your results. 18

23 Refer to the background information provided above. Can you make a reasonable hypothesis about the type of radiation (alpha, beta, or gamma) that is primarily emitted by uranium? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 19

24 Station FF03: Charging by Contact Purpose The purpose of this activity is to experience the transfer of charge from one object to another by contact, and to detect excess electric charge using an electroscope. Physics TEKS 2(F)demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, Physics EOC Reporting Category 2: Gravitational, Electrical, Magnetic, and Nuclear Forces The student will demonstrate an understanding of gravitational, electrical, magnetic, and nuclear forces. Background Information: Everyday matter is made of atoms and molecules. Atoms and molecules are electrically neutral since they normally have equal numbers of positive protons and negative electrons. But some materials gain or lose electrons when they rub against each other. This gives us an easy way to create charged objects. Maybe you have noticed that after you comb your hair, the comb often becomes electrically charged. The charged comb can even pick up little pieces of paper. Essential Question: How can you detect the presence of a charge on an object? Materials: Electrostatics Materials Kit shown below 20

25 Activities and Questions: Build a simple electroscope by hanging one of the small pith balls from a thread. Tape the thread to the edge of the table or desk so that the ball is hanging about 20 cm below the edge. Now experiment with the rods and fabrics by rubbing a rod with a piece of fabric, then touching the rod to the hanging ball. Now take a different rod and rub with a piece of fabric. Then bring the rod near the hanging ball so it is close but not touching it. What happens? Can you explain what you see? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 21

26 Station FF04: Multimeters and Ohm's Law Purpose The purpose of this activity is to predict the current flowing in a simple circuit using Ohm s Law and to use a multimeter as an ammeter to measure the current. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), Science concepts. The student knows the nature of forces in the physical world. 5(E) characterize materials as conductors or insulators based on their electrical properties; Supporting Standard 5(F) design, construct, and calculate in terms of current through, potential difference across, resistance of, and power used by electric circuit elements connected in both series and parallel combinations; Readiness Standard Physics EOC Reporting Category 2: Gravitational, Electrical, Magnetic, and Nuclear Forces The student will demonstrate an understanding of gravitational, electrical, magnetic, and nuclear forces. Background Information: A material that is a poor conductor reduces the flow of current (if the material is a really bad conductor, no current flows at all, and we say the material is an insulator.) A small piece of poor conductor is called a resistor, and the resistance is a number that tells us how much the resistor will resist the flow of current. The unit of resistance is the Ohm, symbolized by the Greek letter omega, Ω. So a resistor with a resistance of 3 Ω is still a pretty good conductor, but if the resistance is 3000 Ω, the resistor is not a good conductor at all. Ohm s Law is a simple equation that you can use to predict the current that will flow through a resistor if you hook it up to a battery of voltage, V. Ohm s Law says: Current = voltage/resistance or, in symbols, I = V/R Essential Question: How much current will flow through a resistor when a potential difference is applied across the resistor? Materials: Digital multimeter Solderless breadboard 9-volt battery and battery clip Resistor, 500 Ω - the colors should be: green-brown-brown-gold (as shown on the diagram below) 22

27 Source: Activities and Questions: You will build this simple DC circuit on your breadboard. 23

28 Before you connect the battery, make sure your meter is set to read amperes or milliamperes (ma or ma will be shown on the multimeter). Using Ohm s Law, with the potential difference, V, equal to 9 volts, what do you calculate as the current that should flow through the circuit? Now connect your battery and read the current. Remember that Ohm s Law gives the current in amperes. If your meter reads milliamperes you need to divide by 1000 (move the decimal 3 places to the left) to convert milliamperes to amperes. How close is your prediction? What would happen to the current if you added a second resistor in series with the first? Why? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 24

29 Station ME01: Getting to Know a Ballistic Pendulum Purpose The purpose of this activity is to become familiar with a ballistic pendulum. You will make some connections between the concepts of momentum, kinetic energy, and gravitational potential energy. You will also remind yourself of the difference between elastic and inelastic collisions. Physics TEKS 2(G) use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as ripple tank with wave generator, wave motion rope, micrometer, caliper, radiation monitor, computer, ballistic pendulum, electroscope, inclined plane, optics bench, optics kit, pulley with table clamp, resonance tube, ring stand screen, four-inch ring, stroboscope, graduated cylinders, and ticker timer; (6) Science concepts. The student knows that changes occur within a physical system and applies the laws of conservation of energy and momentum. 6(B) investigate examples of kinetic and potential energy and their transformations [Readiness Standard] 6(C) calculate the mechanical energy of, power generated within, impulse applied to, and momentum of a physical system [Readiness Standard] 6(D) demonstrate and apply the laws of conservation of energy and conservation of momentum in one dimension [Readiness Standard] Physics EOC Reporting Category 3: Momentum and Energy The student will demonstrate an understanding of momentum and energy. Background Information: Measuring the speed of a bullet or other projectile is a challenge. They are often moving way too fast to use a motion sensor or even an ordinary video camera or digital video recorder. But we know that a moving mass has kinetic energy, so if we can find some clever way to measure the kinetic energy of the bullet we can solve for v to find its speed. Refer to the diagram below of the ballistic pendulum. Source: 25

30 With a ballistic pendulum, a projectile is shot into a pendulum bob at rest. The bullet gets stuck in the bob. After the crash, the bob+bullet swings upward, gaining potential energy. If the maximum height is measured, we can calculate the potential energy (mgh) of the bob+bullet. Does that potential energy equal the original kinetic energy of the bullet? No, because a lot of that original energy was dissipated as heat and sound during the crash into the pendulum bob. So we need to be a little more clever. Where did the final potential energy come from? Although it s not equal to the kinetic energy (KE) of the bullet before it crashed, the final potential energy (PE) is equal to the kinetic energy of the bob with the bullet in it when they took off right after the crash. We can calculate backwards: mgh = ½ Mv 2, where PE of bullet+bob at top of swing = KE of bullet+bob right after crash M=(mass of bob +mass of bullet) v =(speed of bob+bullet right after crash) From this KE, we can calculate the velocity, v, of the bob+bullet right after the crash. As a bonus, we can now calculate the MOMENTUM of the bob+bullet right after the crash. Momentum is just Mv. Now consider the bullet right before it hit the bob. The bullet had some initial momentum, mv, and this is the v we want to find. Momentum is conserved, even in inelastic collisions where energy is lost. So now we can say: mv (bullet before crash) = Mv (bob + bullet after crash) Solve for v and you have the original speed of the bullet! You may be relieved to know that we are not going to go through all these calculations during our first look at the ballistic pendulum. But we do want to fire it, and answer some reasonable questions about what we observe. Essential Question: How can we use the conservation of energy and the conservation of momentum to calculate an initial velocity, even if energy is not conserved throughout the process? Materials: Ballistic pendulum apparatus Projectile (this will serve as our bullet ) Safety goggles 26

31 Activities and Questions: Put on your safety goggles to protect your eyes from the projectile that you will launch! Fire the steel projectile and note that the yellow pointer records the angle made by the swinging bob at its highest point. You could use trigonometry to figure out the height that the bob rose above its original position, but you could also use rulers to do that. Maximum height in meters: m The mass of the pendulum bob is 35 g and the mass of the steel projectile bullet is 8.3 g. Calculate the potential energy gained by the bob + bullet when it was at its highest point: Joules 1. Is your answer less than, nearly equal to, or greater than the KE of the bob+bullet right after the crash? 2. Is your answer less than, nearly equal to, or greater than the KE of the bullet right before the crash? 3. Would the final height of the bob+bullet have been greater than, equal to, or less than your steel ball measurement if you instead had fired an aluminum ball at the same initial speed? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 27

32 Station ME02: Potential and Kinetic Energy Purpose The purpose of this activity is to look at the visible result of kinetic energy being converted to potential energy, and vice versa, on a simple roller coaster toy. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, Science concepts. The student knows that changes occur within a physical system and applies the laws of conservation of energy and momentum. The student is expected to 6(A) investigate and calculate quantities using the work-energy theorem in various situations; Readiness Standard 6(B) investigate examples of kinetic and potential energy and their transformations; Readiness Standard EOC Reporting Category 3: Momentum and Energy The student will demonstrate an understanding of momentum and energy. Background Information: The law of conservation of energy says that energy cannot be created or destroyed, but it can be transformed from one form to another. We will consider the transformation of energy as a marble moves along a potential kinetic track. Essential question: What does the conversion between potential and kinetic energy look like on a simple, low friction track? Materials: Marble Demonstration Potential Kinetic Track as shown below Source: 28

33 Activities and Questions: As an object moves around in the gravitational field of the earth, what will you see happening if the gravitational potential energy of the object in increasing? What will you see happening as the kinetic energy of the object is increasing? Release the marble from the high end of the track and observe as it approaches the first low point. Describe what is happening to the height and the speed of the marble as it approaches the low point. Describe what is happening to the potential and kinetic energy of the marble as it approaches the low point. Now watch as the marble approaches a high point on the track. Describe what is happening to the height and the speed of the marble as it approaches the high point. Describe what is happening to the potential and kinetic energy of the marble as it approaches the high point. Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 29

34 Station ME03: Conservation on a Ramp Purpose The purpose of this activity is to measure the kinetic and potential energy at two positions of an object moving on a low-friction ramp. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, Science concepts. The student knows that changes occur within a physical system and applies the laws of conservation of energy and momentum. The student is expected to 6(A) investigate and calculate quantities using the work-energy theorem in various situations; Readiness Standard 6(B) investigate examples of kinetic and potential energy and their transformations; Readiness Standard EOC Reporting Category 3: Momentum and Energy The student will demonstrate an understanding of momentum and energy. Background Information: By now you have learned that the sum of kinetic and potential energy of a moving object will be conserved if gravity is the only force doing work on the system. This would mean that if an object slides down a frictionless ramp starting at rest, the object s potential energy at the top of the ramp will be equal to the kinetic energy at the bottom. This is because at the top, the object was at rest so v= 0 m/s, and since kinetic energy is 1/2mv 2, the kinetic energy was also 0 joules. But gravitational potential energy is mgh so if the top of the ramp is h meters above the bottom, the object has potential energy mgh at the top. The object s total energy at the top is then 0 joules of KE + mgh joules of PE. Now think about the bottom of the ramp. Now the object has no PE because the height is 0 meters so mgh is also 0 joules. But now the object is moving because it sped up as it slid down the ramp. So it has a velocity v m/s so the KE is ½ mv 2. Now the total energy is ½ mv 2 of KE + 0 joules of PE. So if the total energy is the same at the top and bottom, we can conclude that PE at the top = KE at the bottom. We will attempt to test this in this experiment. We can measure the PE at the top just by measuring the height of the top of the ramp and finding the mass of the cart, then multiplying to get mgh. We can measure the KE at the bottom by measuring the velocity of the cart with a photogate and calculating ½ mv 2 to get the KE. We will see how close these two are to one another. 30

35 Essential question: Will measurement show that the potential energy of an object released at the top of a ramp is equal to the kinetic energy at the bottom? Materials: Vernier photogates Vernier track Vernier dynamics cart LabQuest Activities and Questions: Prop up the track at one end with a couple of books. Use a ruler to measure the height of the propped-up end. Weigh your cart and find its mass in kilograms. Now calculate the PE of the cart when it is at the top of the ramp. Set up a photogate at the bottom of the ramp as shown above and set your LabQuest to measure in pulse mode. Start collecting data and release the cart from the top of the ramp. Collect the velocity of the cart from the LabQuest data. Now calculate the KE of the cart at the bottom. Were your two energy measurements close? What do you think might account for any differences in the measured energies? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 31

36 Station WQ01: Guess the Gas Purpose The purpose of this activity is to remind you of what you know about atomic transitions and how they determine the color of gas discharges. You will also get to review the electromagnetic spectrum. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including... discharge tubes with power supply (H, He, Ne, Ar) Science concepts. The student knows the characteristics and behavior of waves. 7(C) compare characteristics and behaviors of transverse waves, including electromagnetic waves and the electromagnetic spectrum, and characteristics and behaviors of longitudinal waves, including sound waves [Supporting Standard] Physics EOC Reporting Category 4: Waves and Quantum Phenomena The student will demonstrate an understanding of waves and quantum phenomena. Background information: The Electromagnetic Spectrum The diagram above shows the visible wavelengths in the electromagnetic spectrum. Some reference wavelengths are indicated; these wavelengths are given in units of Angstroms (1 Angstrom = 1x10-10 m). For example, light with a wavelength of 6600 Angstroms would appear to our eyes to be a deep orange color. Atomic transitions When electric current is passed through a gas, the electrons in each gas molecule become excited by absorbing energy from the electric current. But the electrons do not remain excited for long; after just a few milliseconds, the electrons relax to a lower state of energy. These processes of becoming excited and relaxing are called atomic transitions. 32

37 What happens to the excitation energy when the electron relaxes? You know that energy is conserved, so the energy must go somewhere. What happens is that the electron emits ( gives off ) the energy in the form of light. That s why neon signs, traffic lights, and fluorescent lights glow. They contain gases that are constantly being excited, then relaxing, as electric current passes through the tube of gas. Because of the quantum nature of electron behavior, electrons in an atom can only absorb and release very specific amounts of energy. This amount depends on the type of atom. Therefore, the light emitted by different atoms is of different colors, and the color can be used to identify the type of atom in the gas. (In reality, electrons in a gas atom can emit several specific energies of light, but usually one of these is strongest and gives the glowing gas its visible color.) Essential question: What is the nature of the light given off by the electrons in glowing atoms? Materials: Gas discharge power supply Gas discharge tubes: Argon, Helium, and Neon Activities and Questions: Suppose that your teacher told you that the gas discharge tubes had gotten mixed up in the storeroom and the labels had fallen off. The teacher remembers that the tubes contained helium, argon, and neon but didn t know which was which. Your job is to identify each tube. You know that physicists have studied the emission spectra of gases very well, and published the results so you do a bit of research and find the following table of the emission spectra of the noble gases: Noble gas Wavelength(s) of dominant electronic transitions, Angstroms Helium (He) 5876; 6678 Neon (Ne) 6334; 6383; 6402 Argon (Ar) 4198 Now you need to observe the emission spectrum of the mixed up tubes which your teacher has labeled A, B, and C. CAUTION! The power supply produces a dangerous HIGH VOLTAGE, GREATER THAN 1000 VOLTS and must be treated with respect. It is dangerous if misused. Do not turn on the power yet! Carefully insert tube A into the power supply as shown below. DO NOT TURN ON THE POWER SUPPLY IF THERE IS NO TUBE IN PLACE. Once the tube is in place, turn on the power supply. 33

38 Tube Color of Discharge The wavelength might be: Now consult the colored figure of the spectrum and make a reasonable prediction of which gas is in which tube. Tube A B C Type of Noble Gas You Predict Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 34

39 Station WQ02: Converging Lenses - Find the Focal Length Purpose The purpose of this activity is to see how the thin-lens equation allows you to predict where an image will be formed by a converging lens. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, Science concepts. 8(E) describe and predict image formation as a consequence of reflection from a plane mirror and refraction through a thin convex lens [Supporting Standard] Physics EOC Reporting Category 4: Waves and Quantum Phenomena The student will demonstrate an understanding of waves and quantum phenomena. Background Information: When a ray of light passes from air into a flat plate of glass, the rays are refracted, or bent. If the glass surface is not flat, the light is still refracted, and if the shape of the glass is just right, the light can be brought together to form an image on the opposite side of the glass. This is the converging lens and a magnifying glass is a good example. We can use the thin lens equation to predict where the image will be formed. This image distance depends on the focal length of the lens, and on the object distance, which is the distance between the object and the lens. Here is the thin-lens equation: 1! = 1!! + 1!! If you put an object at a distance from the lens and measure the distance to the image that is formed, you can rearrange the thin-lens equation to find the focal length of the lens:!! =!!!!!!! (In your calculator, the right side of this equation can easily be entered as: ( (!! )!! +!!!! )!!. Another important thing to know about the focal length of a lens, is that if the object is very far away (like maybe 10 meters away), the image will be formed almost exactly at the focal length. Essential question: How do we measure the focal length of a converging lens? 35

40 Materials: Vernier track Vernier Optics Expansion Kit Activities and Questions: Set up the Vernier track with the converging lens, light, and screen from the Optics Expansion Kit as shown below. Note: You will not use all parts of the kit. Move the light (this is the object ) until you get a clear image on the screen. Measure the object distance from the lens and image distance from the lens. Use the thin-lens equation above to calculate the focal length of the lens. Now remove the lens and use it to form a clear image of a distant bright object, such as a ceiling light or a window (to be distant, the light or window should be at least 4 meters from the lens). When you get a clear image, the distance to the lens should be very nearly equal to the focal length of the lens. Measure this distance. Did these two methods of measuring the focal length of the lens give similar results? Which do you think is a more reliable method? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 36

41 Station WQ03: Resonance Purpose The purpose of this activity is to see how sound waves will resonate in a pipe if the pipe is of the appropriate length compared to the length of a sound wave. Physics TEKS 2(F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90- degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, Science concepts. 7(B) investigate and analyze characteristics of waves, including velocity, frequency, amplitude, and wavelength, and calculate using the relationship between wavespeed, frequency, and wavelength; [Readiness Standard] 7(C) compare characteristics and behaviors of transverse waves, including electromagnetic waves and the electromagnetic spectrum, and characteristics and behaviors of longitudinal waves, including sound waves [Supporting Standard] 7(D) investigate behaviors of waves, including reflection, refraction, diffraction, interference, resonance [Readiness Standard] Physics EOC Reporting Category 4: Waves and Quantum Phenomena The student will demonstrate an understanding of waves and quantum phenomena. Background Information: When any kind of wave is trapped it can bounce back and forth. You are probably familiar with this from playing with waves on a rope or Slinky. If the wave that travels up and down the rope has just the right wavelength, so that ½, or 1, or 1 ½, or 2 etc. waves fit on the length of the rope, the wave will interfere with itself as it travels back and forth. You can see the standing wave form and appear to stand still. Essential question: How can the wave nature of sound explain the occurrence of resonance in a pipe? 37

42 Materials: Resonance pipes kit as show below Source: Activities and Questions: Strike the tuning fork to get it vibrating. Tuning forks are made in a shape that can only vibrate at one frequency, so as the tuning fork shakes the air around it a sound travels away at a single frequency. We hear this single frequency as a particular pitch. As the tuning fork is vibrating, hold it over the opening of each pipe, one at a time. Do you notice anything different among the different pipes? Record your observations. How can you explain what you observe? Before You Leave Because other groups are going to do this activity after you, be sure to organize all of the materials at this station the way you found them. If you have questions, ask your teacher. 38