《The Physics of Experimental Method》

1INTRODUCTION1

The Place of Experiment in Physical Science1

2ERRORS AND THE TREATMENT OF EXPERIMENTAL RESULTS6

2．1 Introduction6

2．2 Types of Experimental Error6

2．3 Systematic Errors8

2．4 Random Errors10

2．5 The Mean12

2．6The Law of Errors15

Table 2．1 Useful Quantities connected with the Error Integral17

2．7 The Rejection of Observations19

2．8The Combination of Errors20

Table 2．2 Combination of Errors21

2．9 An Application of Least Squares—fitting a Relation to Experimental Results21

2．10 Other Applications of Least Squares24

2．11 Non-Gaussian Distributions25

2．12 The Poisson Distribution26

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

Appendix to Chapter 2＆by J．Maddox29

2．14 General Principles29

2．15 Logarithm Tables30

2．16 Other Mathematical Tables31

2．17 Slide Rules31

2．18 Calculating Machines31

2．19 Curve Fitting32

2．20Polynomial Form33

Table 2．3 Fitting a Polynomial35

2．21Trigonometric Approximation36

Table 2．4 A Harmonic Analysis37

2．22 Other Forms of f(x)39

2．23 The Significance of Least-Squares Calculations40

2．24 The Solution of Simultaneous Linear Equations43

2．25Systematic Elimination44

Table 2．5 Solution of a Set of Simultaneous Equations48

2．26The Relaxation Method49

Table 2．6 Table2．7 Example of Relaxation49

2．27 The Accuracy of Solutions51

2．28 Numerical Integration53

2．29The Use of Quadrature Formulae54

Table 2．8 Examples of Quadrature57

2．30The Accuracy of Numerical Integration57

Table 2．9 Errors of Quadrature Formulae59

3MECHANICAL DESIGN61

3．1 Introduction61

3．2 Kinematics61

3．3Kinematic Design62

Table 3．1 Loading of Ball-Plane Contacts64

3．4 One Degree of Translation—the Kinematic Slide66

3．5 One Degree of Freedom—Rotation69

3．6 Summary of the Uses of Kinematic Designs72

3．7 Motional Hysteresis—the Use of Spring Constraints73

3．8 Sine and Cosine Errors in Measuring Instruments75

3．9 The Control of Translational Motion76

3．10 Centring Errors—the Measurement of Rotation79

3．11 The Size of Physical Apparatus—General Considerations80

3．12 Example—Rotating Wheels82

3．13 The Size of Instruments—Other Examples83

3．14 The Size of Physical Apparatus—Thermal Considerations84

3．15 The Balancing of Instruments86

3．16 Dynamic Balance87

3．17 Mechanical Disturbances—Anti-Vibration Supports89

3．18 Practical Forms of Anti-Vibration Support91

Appendix 1 Some Points of Design93

Appendix 2Selected Engineering Formulae97

Table 3．2 Data on Loaded Beams97

Table 3．3 Second Moments of Sections98

Table 3．4 Stability of Struts98

Table 3．5 Circular Shafts99

Table 3．6 Wall Stresses in Pressure Vessels100

4MATERIALS OF CONSTRUCTION101

4．1 Introduction101

4．2 Metals—Mechanical Properties101

4．3Steels—Iron Alloys containing Carbon104

Table 4．1 Plain Carbon Steels104

Table 4．2 Tempering of Tool Steel106

4．4 Alloy Steels106

4．5 Invar and Elinvar107

4．6 Copper and its Alloys108

4．7 Copper-Zinc Alloys—Brasses108

4．8 Copper-Tin Alloys—Bronze and Gun Metal109

4．9 Copper-Nickel Alloys109

4．10 Copper-Beryllium110

4．11 Aluminium and Light Alloys110

4．12The Jointing of Metals—Soldering111

Table 4．3 Solders113

4．13 Plastic Cements for Metals115

4．14Metals for Electrical Purposes115

Table 4．4 Commercially Pure Metals for Electrical Purposes116

4．15Alloys for Electrical Purposes116

Table 4．5 Alloys with important Electrical Properties117

Table 4．6 Thermocouples118

4．16Magnetic Materials(Soft)116

Table 4．7 Soft Magnetic Materials120

4．17Magnetic Materials(Hard)121

Table 4．8 Representative Permanent Magnetic Materials123

4．18 Ferrites124

4．19 Non-Magnetic Materials125

4．20 Insulating Materials126

4．21Plastics126

Table 4．9 High-Temperature Insulators127

Table 4．10 General Purpose Insulators130

Table 4．11 Insulators for Electrometer Circuits131

Table 4．12 Notes on Insulating Materials132

Table 4．13 Plastics133

4．22 Note on the Materials of Table 4．13 and some other Plastics135

4．23 Glass137

4．24 Glass as a Mechanical Material138

4．25Glassblowing139

Table 4．14 Properties of Glasses140

4．26 Fused Quartz142

4．27Quartz Fibres143

Table 4．15 Torsion Constants and Tensile Strengths of Quartz Fibres143

Appendix to Chapter 4 Small Laboratory Furnaces145

5VACUUM TECHNIQUE147

5．1Introduction147

Table 5．1 Molecular Quantities147

5．2Pumping Speeds148

Table 5．2 Pumping Speeds of Connections150

5．3The Principles of Vacuum Pumps151

Table 5．3 Diffusion Pump Fluids154

5．4The Measurement of Low Pressures—Vacuum Gauges157

Table 5．4 Vacuum Gauges158

5．5 Getters162

5．6 Static and Kinetic Vacuum Systems164

5．7 Static Vacuum Systems—Arrangement165

5．8 Static Vacuum Systems—Construction165

5．9Static Vacuum Systems—Procedure167

Table 5．5 Typical Evacuation Schedule168

5．10 Kinetic Vacuum Systems168

5．11 Ultra-high Vacuum174

5．12 Leaks175

Appendix 1Seals between Metal and Glass177

Quartz-Metal Seals180

Appendix 2 Spot-Welding181

Appendix 3 Materials Important in Vacuum Technique182

6ELECTRICAL MEASUREMENTS AND MAGNETIC FIELDS185

6．1 Electrical Measurements185

6．2 Deflection Instruments for Direct Current185

6．3Ammeters and Voltmeters186

Table 6．1 Accuracy of Electrical Instruments186

6．4 Recording Instruments188

6．5 Moving Coil Galvanometers190

6．6The Practical Use of Moving Coil Galvanometers190

Table 6．2 Representative Galvanometer Sensitivities191

6．7 Galvanometers of High Performance192

6．8 Theory of Moving Coil Galvanometers193

6．9 Deflection Amplifiers196

6．10 D．C．Potentiometer and Bridge Measurements197

6．11A．C．Measurements198

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

6．12 A．C．Bridge Measurements199

6．13 Valve Voltmeters202

6．14 The Measurement of Small Currents203

6．15 The Arrangement of Circuits for Small Current Measurements206

6．16 The Choice of an Electrometer207

6．17 Valves as Electrometers208

6．18 The Production and Measurement of Magnetic Fields211

6．19 Coreless Coils211

6．20 Electromagnets213

6．21 The Measurement of Magnetic Fields218

Appendix to Chapter 6 Electric Motors221

7ELECTRONICS226

7．1 Electronic Aids226

7．2 Power Supplies226

7．3 Amplifiers232

7．4 The Triode Voltage Amplifier235

7．5 Inter-Electrode Capacities and the Miller Effect237

7．6 The Screen-grid Valves—Tetrode and Pentode238

7．7 The Properties of a Pentode239

7．8 The Complete Amplifying Stage239

7．9The Frequency Characteristics of R．C．Amplifier Stages241

Table 7．1 Development of Pentodes243

7．10 The Design of Amplifier Stages244

7．11 The Feedback Principle246

7．12 The Feedback Principle—Quantitative247

7．13 The Cathode Follower249

7．14＂Voltage＂and＂Current＂Feedback Amplifiers251

7．15 Stability Limitation of the Feedback Principle253

7．16 Balanced or Push-Pull Amplifiers254

7．17 D．C．Amplifiers256

7．18 The Valve as an Electrometer259

7．19 Valve Oscillators259

7．20 Tuned Circuit Oscillators259

7．21 The Resistance-Capacity Oscillator261

7．22 Aperiodic Feedback—Multivibrators262

7．23 Pulse Operation of Valve Circuits268

7．24 The Use of Diodes272

7．25 Very Rapid Pulses,Transmission Lines273

7．26Semiconductor Electronics275

Table 7．2 Semiconductor Devices278

7．27 Transistors279

7．28 Transistor Circuits—Amplifiers282

7．29 Transistor Circuits—Laboratory Control Circuits287

7．30 Transistor Circuits—Oscillators289

7．31 Transistor Circuits—Relaxation Oscillators and Derivatives291

7．32 Comparison of Transistors and Valves293

Appendix to Chapter 7 Relay Systems294

8OPTICS AND PHOTOGKAPHY298

8．1 Optics and Photography298

8．2 Illumination298

8．3Brightness of an Object298

Table 8．1 Quantities used in Analysis of Illumination299

8．4 Brightness of an Image301

8．5Typical Illuminating Systems305

Table 8．2 Light Sources310

Table 8．3 Special and Improvised Light Sources312

8．6 Light Sources313

8．7 The Eye as an Optical Instrument314

8．8 The Acuity of Vision314

8．9 The Colour and Intensity Response of the Eye316

8．10 The Behaviour of the Eye at Low Intensity—Ultimate Sensitivity317

8．11 Image-Producing Optical Systems319

8．12 Aberrations319

8．13 Telescope Objectives324

8．14 The Choice and Use of a Telescope325

8．15Microscope Objectives327

Table 8．4 Typical Performance of Microscope Objectives328

8．16 Illumination in the Microscope330

8．17 The Use of the Microscope331

8．18 Eyepieces333

8．19 Photographic Objectives336

8．20Depth of Focus337

Table 8．5 Representative Performances of Photographic Lenses338

8．21 Projection Lenses339

8．22 Reflecting Optical Systems339

8．23Anti-Reflection Coatings341

Table 8．6．Optical Applications of Thin Films344

8．24 Photography345

8．25 The Quantitative Behaviour of Photographic Materials346

8．26 The Reciprocity Law349

8．27 Characteristics of Emulsions—Colour Sensitivity350

8．28Characteristics of Emulsions352

Table 8．6 Typical Characteristics of Negative Materials352

8．29 The Choice of a Photographic Material353

8．30 The Manipulation of Photographic Materials in the Laboratory354

8．31 Photometry—The Measurement of Light Intensity356

8．32Photographic Photometry357

Table 8．7 Methods of Attenuating Light for Plate Calibration358

Table 8．8 Detectors for Microphotometers359

Appendix 1 The Setting Up of Optical Systems360

Appendix 2Optical Materials362

Table 8．9 Refractive Properties of Glasses364

9THE DETECTION OF ELECTROMAGNETIC RADIATION368

9．1 Introduction368

9．2 Photocathodes and Photoemissive Cells370

9．3 Note on Photocathodes in Commercial Tubes371

9．4 Photocells and Photomultipliers373

9．5 Application of Photocells and Photomultipliers374

9．6 Photoelectric Detectors in the Ultraviolet377

9．7Solid-state Photoelectric Detectors378

Table 9．1 Solid-state Radiation Detectors380

9．8 Non selective(thermal)Detectors381

Appendix to Chapter 9 Note on the Comparison of Detectors for Small Amounts of Light384

10THE NATURAL LIMITS OF MEASUREMENT386

10．1 The Natural Limits of Measurement386

10．2 Thermal Agitation387

10．3 Thermal Noise in Electrical Circuits388

10．4 Thermal Motion in Galvanometer Measurements390

10．5Further Fluctuation Phenomena in Electrical Circuits392

Table 10．1 Noise in Valves—Empirical Data394

10．6 Flicker Noise and Semi-conductor noise396

10．7 Examples．An Audio-Frequency Amplifier397

10．8 A Radar Receiver398

10．9 An Amplifier used in conjunction with an Ionisation Chamber399

10．10 A Photocell used to detect Weak Light402

10．11 The Coherent Rectifier System404

11SOME TECHNIQUES OF NUCLEAR PHYSICS408

11．1Ionisation by Ionising Particles408

Table 11．1 Average Energy required to produce an Ion Pair410

11．2 The Motion and Collection of Ions411

11．3 Electron Collection Chambers413

11．4 Ion-Collection Chambers416

11．5 Gas Multiplication—Proportional Counters417

11．6 The Geiger Counter418

11．7 The Construction of Counters421

11．8 The Geiger Counter in Use423

11．9Scintillation Counters425

Table 11．2 Scintillators for Particle Detection427

Table 11．3 Conversion Processes for γ-rays in Scintillator428

11．10 Neutron Counting430

11．11 Some Special Counting Methods432

11．12 Coincidence Counting434

11．13 Anti-coincidence Counting435

11．14 Electronic Devices for Nuclear Research436

11．15Errors and Statistics in Counting453

Table 11．4 Random Counting Rates for 0．1% Loss of Counts455

11．16 The Cloud Chamber456

11．17 The Bubble Chamber459

11．18 Nuclear Track Emulsions460

References464

Index475