125 Physics Projects for the Evil Genius (2 page)

BOOK: 125 Physics Projects for the Evil Genius
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Project 51 Linear momentum. Where can you find a perfect 90-degree angle in nature?

Project 52 Elastic collisions
.

Project 53 Inelastic collision. Sticking together
.

Project 54 Impulse and momentum. Eggstreme physics
.

Project 55 Using gravity to move a car
.

Project 56 How can CSI measure muzzle velocity? The ballistic pendulum
.

Project 57 Angular momentum. Riding a bike
.

Project 58 Moment of inertia. Ice skaters and dumbbells
.

Project 59 What caused Voyager to point in the wrong direction?

Project 60 Moment of inertia. The great soup can race or that’s how I roll
.

Project 61 Making waves. I thought I node this
.

Project 62 Rolling uphill
.

Project 63 Getting around the loop. From how far above the ground does the roller coaster need to start?

Section 6 Sound and Waves

Project 64 What does sound look like? Oscilloscope wave forms
.

Project 65 Ripple tank
.

Project 66 Simple harmonic motion. The swinging pendulum
.

Project 67 Simple harmonic motion. The spring pendulum
.

Project 68 Generating sine waves
.

Project 69 Natural frequency
.

Project 70 Bunsen burner pipe organ. Resonant frequency
.

Project 71 Springs and electromagnets. Resonance
.

Project 72 Speed of sound. Timing an echo old school. Why Galileo couldn’t do this with light
.

Project 73 Speed of sound. Resonance in a cylinder
.

Project 74 Racing against sound. Doppler effect
.

Project 75 Adding sounds. Beat frequency
.

Project 76 Pendulum waves
.

Project 77 Using waves to measure the speed of sound
.

Section 7 Light

Project 78 Ray optics. Tracing the path of light using a laser
.

Project 79 Two candles, one flame
.

Project 80 Laser obstacle course
.

Project 81 Light intensity. Putting distance between yourself and a source of light
.

Project 82 How do we know that light is a wave? Thomas Young’s double slit experiment with a diffraction grating
.

Project 83 How to measure the size of a light wave
.

Project 84 The speed of light in your kitchen. Visiting the local hot spots
.

Project 85 Refraction. How fast does light travel in air or water?

Project 86 Polarization. Sunglasses and calculator displays
.

Project 87 What is the wire of a fiber-optic network? Total internal reflection using a laser and a tank of water
.

Project 88 The disappearing beaker
.

Section 8 Hot and Cold

Project 89 How much heat is needed to melt Greenland? Heat of fusion
.

Project 90 A water thermometer
.

Project 91 What is the coldest possible temperature? Estimating absolute zero
.

Project 92 Liquid nitrogen
.

Project 93 Boiling water in a paper cup
.

Project 94 Boiling water with ice
.

Project 95 Seebeck effect/Peltier effect. Semiconductor heating
.

Section 9 Electricity and Magnetism

Project 96 Static charges
.

Project 97 Making lightning. The van de Graaff generator
.

Project 98 The Wimshurst machine. Separating and storing charges
.

Project 99 Running into resistance. Ohm’s law
.

Project 100 Circuits: Bulbs and buzzers
.

Project 101 How does heat affect resistance?

Project 102 Resistivity. Can iron conduct electricity better than copper?

Project 103 Storing charge. Capacitors
.

Project 104 Is the magnetic force more powerful than gravity?

Project 105 Magnetic levitation using induction. Electromagnetic ring tosser
.

Project 106 Magnetic levitation using superconductivity. The Meissner effect
.

Project 107 Moving electrons produce a magnetic field. Oersted’s experiment. The magnetic field of a current-carrying wire
.

Project 108 Faraday’s experiment. Current generated by a magnet
.

Project 109 If copper is not magnetic, how can it affect a falling magnet? Lenz’s law
.

Project 110 Effect of a magnet on an electron beam. The right-hand rule for magnetic force
.

Project 111 What is the shape of a magnetic field?

Project 112 What happens to a current-carrying wire in a magnetic field?

Project 113 A no-frills motor
.

Project 114 Magnetic accelerator
.

Project 115 Alternating current
.

Project 116 The diode. An electronic one-way valve
.

Section 10 The Earth

Project 117 Measuring the Earth’s magnetic field
.

Project 118 Weighing the Earth
.

Section 11 The Twentieth Century

Project 119 What is the size of a photon?

Project 120 How is a hydrogen atom like the New Jersey Turnpike? Seeing the energy levels of the Bohr atom
.

Project 121 Photoelectric effect
.

Project 122 Millikan oil-drop experiment. Mystery marbles. Understanding how the experiment worked
.

Project 123 Ping-pong ball chain reaction
.

Project 124 The sodium doublet. Why do we think the electron has both up and down spins?

Project 125 Building a cloud chamber. Why muons should not be here. Special relativity
.

Appendix A

Appendix B

Index

Introduction
 
Who This Book Is Written For
 

This book has been written for anyone who is interested in, obsessed with, or simply mildly curious about exploring physics. The experiments in this book are intended to serve as a resource for teachers at all levels to use in planning laboratory activities for their classes and to get ideas for demonstrations. This book can also provide a way for anyone not necessarily directly involved with an academic physics class—including parents, scout leaders, and hobbyists—to pursue the world of physics as far as their interests take them. Young children—and those facilitating their education—will be able to appreciate many of these experiments on an intuitive level—perhaps one day to revisit them in greater depth.

If you are looking for science project ideas, you should be able to find something in these pages to work with. Students involved in a first-year high school or college physics class will find the overall sequence familiar and hopefully won’t have too much trouble finding their way around.

I imagine that readers with a wide range of interests, backgrounds, and available resources will look through these pages for ideas about physics experiments. For this reason, I have written the projects/experiments to be accessible to readers in a number of different ways and on a variety of levels. Most of the experiments include a way to get started without requiring elaborate equipment.

How This Book Is Organized
 

Each section starts with a list of required items followed by step-by-step methods. Because there is often more than one way to do a project, various options are given to accommodate varying experience, available resources, and interest levels among readers.

The expected outcome for the experiments is given to help you interpret your experimental results. First you will find the most qualitative and intuitive insights, followed by increasingly detailed descriptions. For those who are interested (and
only
those who are interested) equations are provided to complete the explanation for why the experiments work. The reader is invited to pursue only as much or as little detail as they care to. This book is not intended to be a textbook on physics theory. I have tried, however, to help readers connect with the next step they might be ready to take. Just to be sure, each project has a conclusion that spells out the point of the experiment.

The World of Physics: Discovery and Rediscovery
 

On more than one occasion in the history of physics, the greatest advances have taken place at a time when the conventional wisdom of the day was that everything had already been discovered and all that was left to work out were the details. The hands-on approach presented here is to help
the reader to (re-)discover physics directly. (All I ask, is in your acceptance speech for the Nobel Prize for physics, you reserve a few kind words for this book.)

There is typically more than one way to do many of these experiments. At least one procedure from start to finish is given for each experiment. But also a range of alternative approaches and extensions can be found for most of them. Hopefully this book will leave you with ideas, not only for how to do these experiments, but also for how to come up with experimental ideas of your own.

What You Will Need: Tool Bin/Parts List
 
The Basics
 

Each of the projects in this book has a specific parts list, called “What you need.” Because different readers will have access to different types of equipment, alternative approaches are presented. A list of major suppliers is given in
Appendix A
at the end of this book.

The following are some of the items you may want to have handy. Most of these items are available in typical physics labs and many can be improvised.

  • stopwatch—a one-tenth-second resolution is sufficient because it easily exceeds human reaction time.
  • ring stands—many of the projects in this book involve supporting or holding other components of the apparatus. While this can be accomplished in other ways, having a basic set of ring stands with a few clamps gives you more time to focus on setting up the experiment.
  • meterstick—most metersticks have millimeter markings. Metersticks often serve multiple functions in addition to measuring, such as holding lenses and mirrors. The thinner ones usually fit better with the supports used in optical experiments.
  • tape measure—most of your work will be in meters. It is easy enough to convert feet to meters, but given the choice, a tape measure with metric divisions is preferable.
  • ruler—with millimeter divisions.
  • spring(s)—springs with varying degrees of stiffness to compare are useful. The best are ones that can be partially stretched by a reasonable weight.
  • pulley—the less friction and the lowest mass, the better.
  • string and rope—various kinds. You will want at least some thin strong string. Weaker string that can break plays a role in
    Project 24
    .
  • mass set—a range of masses from 10 g to 1 kg (1000 g). They should have an attachment point from the top and, ideally, also from the bottom.
  • spring scale—these come in various ranges, from a full scale reading of 2.5 newtons (255 g) to a full-scale reading of 50 newtons (5100 g). If you are doing demonstrations before a group, a large circular version of the scale with oversize lettering is the way to go. (Not to quibble, but weight is a
    force
    that is read in newtons and mass is a measure of an object’s inertia, which is measured in grams. Physics purists definitely prefer weighing objects in newtons.) Most of our work will be in the System International (SI), which, to oversimplify, is a fancy new name for the metric system. Spring scales also come calibrated in pounds (and if you must, dynes, which almost no one uses today)—if you happen to have one, you can do the math. Conversion factors can be found in
    Appenidix B
    .
  • balance—low-end electronic balances have become much more affordable and can be purchased for less than $50. Other options include analog triple-beam scales or the more elaborate digital balances.
  • wire—several meters of insulated wire, such as American wire gauge (AWG) 18, 20, or 22.
  • jumper wires—jumper wires with various combinations of attachments make the electrical projects go a lot smoother. One termination is called a
    banana plug
    , which easily connects a circuit to a meter or a power supply. Another is spring loaded and grips onto an electrical connection called an
    alligator clip
    . (In the UK, some people refer to these “croc” clips. I am
    not
    making this up.)
  • DC power supply (or batteries with a wire connection)—some projects require the capability to adjust the voltage. This requires an adjustable power supply, which can be purchased as a component. The power supply pictured in
    Figure I-1
    (PASCO, part number SE-8828) costs less than $150, and enables you to do all the projects in this book that call for a DC power supply. Reasonably priced DC power supplies can also be purchased from Sargent-Welch, part number WLS-30972-81 or Flinn, part number AP5375.

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