The Physics of Experimental MethodPDF电子书下载

1 INTRODUCTION 1

The Place of Experiment in Physical Science 1

2 ERRORS AND THE TREATMENT OF EXPERIMENTAL RESULTS 6

2．1 Introduction 6

2．2 Types of Experimental Error 6

2．3 Systematic Errors 8

2．4 Random Errors 10

2．5 The Mean 12

2．6 The Law of Errors 15

Table 2．1 Useful Quantities connected with the Error Integral 17

2．7 The Rejection of Observations 19

2．8 The Combination of Errors 20

Table 2．2 Combination of Errors 21

2．9 An Application of Least Squares—fitting a Relation to Experimental Results 21

2．10 Other Applications of Least Squares 24

2．11 Non-Gaussian Distributions 25

2．12 The Poisson Distribution 26

2．13 Mathematical Note on the Statistics of Counting(Poisson Distribution) 27

Appendix to Chapter 2＆by J．Maddox 29

2．14 General Principles 29

2．15 Logarithm Tables 30

2．16 Other Mathematical Tables 31

2．17 Slide Rules 31

2．18 Calculating Machines 31

2．19 Curve Fitting 32

2．20 Polynomial Form 33

Table 2．3 Fitting a Polynomial 35

2．21 Trigonometric Approximation 36

Table 2．4 A Harmonic Analysis 37

2．22 Other Forms of f(x) 39

2．23 The Significance of Least-Squares Calculations 40

2．24 The Solution of Simultaneous Linear Equations 43

2．25 Systematic Elimination 44

Table 2．5 Solution of a Set of Simultaneous Equations 48

2．26 The Relaxation Method 49

Table 2．6 Table2．7 Example of Relaxation 49

2．27 The Accuracy of Solutions 51

2．28 Numerical Integration 53

2．29 The Use of Quadrature Formulae 54

Table 2．8 Examples of Quadrature 57

2．30 The Accuracy of Numerical Integration 57

Table 2．9 Errors of Quadrature Formulae 59

3 MECHANICAL DESIGN 61

3．1 Introduction 61

3．2 Kinematics 61

3．3 Kinematic Design 62

Table 3．1 Loading of Ball-Plane Contacts 64

3．4 One Degree of Translation—the Kinematic Slide 66

3．5 One Degree of Freedom—Rotation 69

3．6 Summary of the Uses of Kinematic Designs 72

3．7 Motional Hysteresis—the Use of Spring Constraints 73

3．8 Sine and Cosine Errors in Measuring Instruments 75

3．9 The Control of Translational Motion 76

3．10 Centring Errors—the Measurement of Rotation 79

3．11 The Size of Physical Apparatus—General Considerations 80

3．12 Example—Rotating Wheels 82

3．13 The Size of Instruments—Other Examples 83

3．14 The Size of Physical Apparatus—Thermal Considerations 84

3．15 The Balancing of Instruments 86

3．16 Dynamic Balance 87

3．17 Mechanical Disturbances—Anti-Vibration Supports 89

3．18 Practical Forms of Anti-Vibration Support 91

Appendix 1 Some Points of Design 93

Appendix 2 Selected Engineering Formulae 97

Table 3．2 Data on Loaded Beams 97

Table 3．3 Second Moments of Sections 98

Table 3．4 Stability of Struts 98

Table 3．5 Circular Shafts 99

Table 3．6 Wall Stresses in Pressure Vessels 100

4 MATERIALS OF CONSTRUCTION 101

4．1 Introduction 101

4．2 Metals—Mechanical Properties 101

4．3 Steels—Iron Alloys containing Carbon 104

Table 4．1 Plain Carbon Steels 104

Table 4．2 Tempering of Tool Steel 106

4．4 Alloy Steels 106

4．5 Invar and Elinvar 107

4．6 Copper and its Alloys 108

4．7 Copper-Zinc Alloys—Brasses 108

4．8 Copper-Tin Alloys—Bronze and Gun Metal 109

4．9 Copper-Nickel Alloys 109

4．10 Copper-Beryllium 110

4．11 Aluminium and Light Alloys 110

4．12 The Jointing of Metals—Soldering 111

Table 4．3 Solders 113

4．13 Plastic Cements for Metals 115

4．14 Metals for Electrical Purposes 115

Table 4．4 Commercially Pure Metals for Electrical Purposes 116

4．15 Alloys for Electrical Purposes 116

Table 4．5 Alloys with important Electrical Properties 117

Table 4．6 Thermocouples 118

4．16 Magnetic Materials(Soft) 116

Table 4．7 Soft Magnetic Materials 120

4．17 Magnetic Materials(Hard) 121

Table 4．8 Representative Permanent Magnetic Materials 123

4．18 Ferrites 124

4．19 Non-Magnetic Materials 125

4．20 Insulating Materials 126

4．21 Plastics 126

Table 4．9 High-Temperature Insulators 127

Table 4．10 General Purpose Insulators 130

Table 4．11 Insulators for Electrometer Circuits 131

Table 4．12 Notes on Insulating Materials 132

Table 4．13 Plastics 133

4．22 Note on the Materials of Table 4．13 and some other Plastics 135

4．23 Glass 137

4．24 Glass as a Mechanical Material 138

4．25 Glassblowing 139

Table 4．14 Properties of Glasses 140

4．26 Fused Quartz 142

4．27 Quartz Fibres 143

Table 4．15 Torsion Constants and Tensile Strengths of Quartz Fibres 143

Appendix to Chapter 4 Small Laboratory Furnaces 145

5 VACUUM TECHNIQUE 147

5．1 Introduction 147

Table 5．1 Molecular Quantities 147

5．2 Pumping Speeds 148

Table 5．2 Pumping Speeds of Connections 150

5．3 The Principles of Vacuum Pumps 151

Table 5．3 Diffusion Pump Fluids 154

5．4 The Measurement of Low Pressures—Vacuum Gauges 157

Table 5．4 Vacuum Gauges 158

5．5 Getters 162

5．6 Static and Kinetic Vacuum Systems 164

5．7 Static Vacuum Systems—Arrangement 165

5．8 Static Vacuum Systems—Construction 165

5．9 Static Vacuum Systems—Procedure 167

Table 5．5 Typical Evacuation Schedule 168

5．10 Kinetic Vacuum Systems 168

5．11 Ultra-high Vacuum 174

5．12 Leaks 175

Appendix 1 Seals between Metal and Glass 177

Quartz-Metal Seals 180

Appendix 2 Spot-Welding 181

Appendix 3 Materials Important in Vacuum Technique 182

6 ELECTRICAL MEASUREMENTS AND MAGNETIC FIELDS 185

6．1 Electrical Measurements 185

6．2 Deflection Instruments for Direct Current 185

6．3 Ammeters and Voltmeters 186

Table 6．1 Accuracy of Electrical Instruments 186

6．4 Recording Instruments 188

6．5 Moving Coil Galvanometers 190

6．6 The Practical Use of Moving Coil Galvanometers 190

Table 6．2 Representative Galvanometer Sensitivities 191

6．7 Galvanometers of High Performance 192

6．8 Theory of Moving Coil Galvanometers 193

6．9 Deflection Amplifiers 196

6．10 D．C．Potentiometer and Bridge Measurements 197

6．11 A．C．Measurements 198

Table 6．3 Deflection Instruments for A．C． 198

6．12 A．C．Bridge Measurements 199

6．13 Valve Voltmeters 202

6．14 The Measurement of Small Currents 203

6．15 The Arrangement of Circuits for Small Current Measurements 206

6．16 The Choice of an Electrometer 207

6．17 Valves as Electrometers 208

6．18 The Production and Measurement of Magnetic Fields 211

6．19 Coreless Coils 211

6．20 Electromagnets 213

6．21 The Measurement of Magnetic Fields 218

Appendix to Chapter 6 Electric Motors 221

7 ELECTRONICS 226

7．1 Electronic Aids 226

7．2 Power Supplies 226

7．3 Amplifiers 232

7．4 The Triode Voltage Amplifier 235

7．5 Inter-Electrode Capacities and the Miller Effect 237

7．6 The Screen-grid Valves—Tetrode and Pentode 238

7．7 The Properties of a Pentode 239

7．8 The Complete Amplifying Stage 239

7．9 The Frequency Characteristics of R．C．Amplifier Stages 241

Table 7．1 Development of Pentodes 243

7．10 The Design of Amplifier Stages 244

7．11 The Feedback Principle 246

7．12 The Feedback Principle—Quantitative 247

7．13 The Cathode Follower 249

7．14＂Voltage＂and＂Current＂Feedback Amplifiers 251

7．15 Stability Limitation of the Feedback Principle 253

7．16 Balanced or Push-Pull Amplifiers 254

7．17 D．C．Amplifiers 256

7．18 The Valve as an Electrometer 259

7．19 Valve Oscillators 259

7．20 Tuned Circuit Oscillators 259

7．21 The Resistance-Capacity Oscillator 261

7．22 Aperiodic Feedback—Multivibrators 262

7．23 Pulse Operation of Valve Circuits 268

7．24 The Use of Diodes 272

7．25 Very Rapid Pulses,Transmission Lines 273

7．26 Semiconductor Electronics 275

Table 7．2 Semiconductor Devices 278

7．27 Transistors 279

7．28 Transistor Circuits—Amplifiers 282

7．29 Transistor Circuits—Laboratory Control Circuits 287

7．30 Transistor Circuits—Oscillators 289

7．31 Transistor Circuits—Relaxation Oscillators and Derivatives 291

7．32 Comparison of Transistors and Valves 293

Appendix to Chapter 7 Relay Systems 294

8 OPTICS AND PHOTOGKAPHY 298

8．1 Optics and Photography 298

8．2 Illumination 298

8．3 Brightness of an Object 298

Table 8．1 Quantities used in Analysis of Illumination 299

8．4 Brightness of an Image 301

8．5 Typical Illuminating Systems 305

Table 8．2 Light Sources 310

Table 8．3 Special and Improvised Light Sources 312

8．6 Light Sources 313

8．7 The Eye as an Optical Instrument 314

8．8 The Acuity of Vision 314

8．9 The Colour and Intensity Response of the Eye 316

8．10 The Behaviour of the Eye at Low Intensity—Ultimate Sensitivity 317

8．11 Image-Producing Optical Systems 319

8．12 Aberrations 319

8．13 Telescope Objectives 324

8．14 The Choice and Use of a Telescope 325

8．15 Microscope Objectives 327

Table 8．4 Typical Performance of Microscope Objectives 328

8．16 Illumination in the Microscope 330

8．17 The Use of the Microscope 331

8．18 Eyepieces 333

8．19 Photographic Objectives 336

8．20 Depth of Focus 337

Table 8．5 Representative Performances of Photographic Lenses 338

8．21 Projection Lenses 339

8．22 Reflecting Optical Systems 339

8．23 Anti-Reflection Coatings 341

Table 8．6．Optical Applications of Thin Films 344

8．24 Photography 345

8．25 The Quantitative Behaviour of Photographic Materials 346

8．26 The Reciprocity Law 349

8．27 Characteristics of Emulsions—Colour Sensitivity 350

8．28 Characteristics of Emulsions 352

Table 8．6 Typical Characteristics of Negative Materials 352

8．29 The Choice of a Photographic Material 353

8．30 The Manipulation of Photographic Materials in the Laboratory 354

8．31 Photometry—The Measurement of Light Intensity 356

8．32 Photographic Photometry 357

Table 8．7 Methods of Attenuating Light for Plate Calibration 358

Table 8．8 Detectors for Microphotometers 359

Appendix 1 The Setting Up of Optical Systems 360

Appendix 2 Optical Materials 362

Table 8．9 Refractive Properties of Glasses 364

9 THE DETECTION OF ELECTROMAGNETIC RADIATION 368

9．1 Introduction 368

9．2 Photocathodes and Photoemissive Cells 370

9．3 Note on Photocathodes in Commercial Tubes 371

9．4 Photocells and Photomultipliers 373

9．5 Application of Photocells and Photomultipliers 374

9．6 Photoelectric Detectors in the Ultraviolet 377

9．7 Solid-state Photoelectric Detectors 378

Table 9．1 Solid-state Radiation Detectors 380

9．8 Non selective(thermal)Detectors 381

Appendix to Chapter 9 Note on the Comparison of Detectors for Small Amounts of Light 384

10 THE NATURAL LIMITS OF MEASUREMENT 386

10．1 The Natural Limits of Measurement 386

10．2 Thermal Agitation 387

10．3 Thermal Noise in Electrical Circuits 388

10．4 Thermal Motion in Galvanometer Measurements 390

10．5 Further Fluctuation Phenomena in Electrical Circuits 392

Table 10．1 Noise in Valves—Empirical Data 394

10．6 Flicker Noise and Semi-conductor noise 396

10．7 Examples．An Audio-Frequency Amplifier 397

10．8 A Radar Receiver 398

10．9 An Amplifier used in conjunction with an Ionisation Chamber 399

10．10 A Photocell used to detect Weak Light 402

10．11 The Coherent Rectifier System 404

11 SOME TECHNIQUES OF NUCLEAR PHYSICS 408

11．1 Ionisation by Ionising Particles 408

Table 11．1 Average Energy required to produce an Ion Pair 410

11．2 The Motion and Collection of Ions 411

11．3 Electron Collection Chambers 413

11．4 Ion-Collection Chambers 416

11．5 Gas Multiplication—Proportional Counters 417

11．6 The Geiger Counter 418

11．7 The Construction of Counters 421

11．8 The Geiger Counter in Use 423

11．9 Scintillation Counters 425

Table 11．2 Scintillators for Particle Detection 427

Table 11．3 Conversion Processes for γ-rays in Scintillator 428

11．10 Neutron Counting 430

11．11 Some Special Counting Methods 432

11．12 Coincidence Counting 434

11．13 Anti-coincidence Counting 435

11．14 Electronic Devices for Nuclear Research 436

11．15 Errors and Statistics in Counting 453

Table 11．4 Random Counting Rates for 0．1% Loss of Counts 455

11．16 The Cloud Chamber 456

11．17 The Bubble Chamber 459

11．18 Nuclear Track Emulsions 460

References 464

Index 475