SCHOOL OF PHYSICS
UNIVERSITY OF MELBOURNE
640-299
GENERAL LABORATORY
2000
NAME…………………………………………………….
SEGMENT………………………………………………...
THESE NOTES WERE REVISED IN 1999 WITH THE ASSISTANCE AND HARD WORK OF
THE FOLLOWING PEOPLE:
ANTON BARTY
CHRIS CHANTLER
JACINTA DEN BESTEN
PHILLIP FOX
AMELIA LIU
LEIGH MORPETH
JUSTINE TILLER
1
Introduction _____________________________________________________ 1
1.1 Experimental Techniques _____________________________________________ 1
1.2 The Report _________________________________________________________ 2
1.3 Deadlines ___________________________________________________________ 6
1.4 Illness ______________________________________________________________ 6
2
Two-slit interference _______________________________________________ 7
2.1 Introduction ________________________________________________________ 7
2.2 Micrometer Calibration _______________________________________________ 7
2.3 Young’s Double Slit __________________________________________________ 9
2.4 Fresnel’s Biprism ___________________________________________________ 11
2.5 Lloyd’s Mirror _____________________________________________________ 14
2.6 References _________________________________________________________ 15
3
The Michelson Interferometer ______________________________________ 16
3.1 Introduction _______________________________________________________ 16
3.2 Introduction To The Michelson Interferometer __________________________ 16
3.3 Fringe Visibility ____________________________________________________ 19
3.4 The Refractive Index of Air ___________________________________________ 21
3.5 References _________________________________________________________ 22
4
Fraunhofer diffraction ____________________________________________ 23
4.1 Introduction _______________________________________________________ 23
4.2 CCD Calibration____________________________________________________ 23
4.3 Single Slit Fraunhofer Diffraction _____________________________________ 26
4.4 Babinet’s Theorem __________________________________________________ 29
4.5 Circular Apertures __________________________________________________ 30
4.6 Multiple Slits _______________________________________________________ 32
4.7 Appendices ________________________________________________________ 34
4.8 References _________________________________________________________ 34
5
Holography _____________________________________________________ 35
5.1 Introduction _______________________________________________________ 35
5.2 Overview __________________________________________________________ 35
5.3 Background Theory _________________________________________________ 35
5.4 Types of holograms__________________________________________________ 38
5.5 Film handling ______________________________________________________ 42
5.6 Viewing holograms __________________________________________________ 43
5.7 Apparatus _________________________________________________________ 43
5.8 Experimental Work _________________________________________________ 43
5.9 References _________________________________________________________ 45
6
Magnets and Magnetic Fields ______________________________________ 46
6.1 Introduction _______________________________________________________ 46
6.2 The Hall Effect _____________________________________________________ 46
6.3 AC Fields __________________________________________________________ 50
6.4 Useful Data ________________________________________________________ 54
6.5 References _________________________________________________________ 54
7
Fundamental Constants ___________________________________________ 55
7.1 Introduction _______________________________________________________ 55
7.2 Charge to Mass Ratio of the Electron___________________________________ 55
7.3 The Photoelectric Effect ______________________________________________ 58
7.4 Useful Data ________________________________________________________ 61
7.5 References _________________________________________________________ 61
8
Waves__________________________________________________________ 62
8.1 Introduction _______________________________________________________ 62
8.2 Acoustics __________________________________________________________ 62
8.3 Microwaves ________________________________________________________ 68
8.4 REFERENCES _____________________________________________________ 77
8.5 APPENDICES _____________________________________________________ 77
9
Properties of Electrons ____________________________________________ 79
9.1 Introduction _______________________________________________________ 79
9.2 Electron Spin Resonance _____________________________________________ 79
9.3 Electron Diffraction _________________________________________________ 85
9.4 Useful Data ________________________________________________________ 89
10  Spectroscopy ___________________________________________________ 90
10.1
Introduction _____________________________________________________ 90
10.2
Background Theory _______________________________________________ 90
10.3
Apparatus _______________________________________________________ 93
10.4
Experiment: Calibrating the Magnet _________________________________ 96
10.5
Experiment: Measuring the Spectrum ________________________________ 97
10.6
Useful Data ______________________________________________________ 99
10.7
References _______________________________________________________ 99
11 Energy loss of alpha particles passing through matter __________________ 100
11.1
Motivation ______________________________________________________ 100
11.2
Background _____________________________________________________ 100
11.3
Measurement of unknown foil thickness _____________________________ 101
11.4
Manufacturing a thin foil __________________________________________ 105
11.5
References ______________________________________________________ 109
12 Gamma ray spectroscopy _________________________________________ 110
12.1
Motivation ______________________________________________________ 110
12.2
The detector system ______________________________________________ 110
12.3
Introductory exercises ____________________________________________ 114
12.4
Detector calibration ______________________________________________ 115
12.5
Identification of unknown sources __________________________________ 118
12.6
Energy resolution ________________________________________________ 118
13 Rutherford Scattering of Alpha Particles ____________________________ 120
13.1
Introduction ____________________________________________________ 120
13.2
Background Theory ______________________________________________ 120
13.3
Apparatus ______________________________________________________ 123
13.4
Experiment: Relationship between Counts and Source to Detector Distance 125
13.5
Experiment: Rutherford Scattering _________________________________ 126
13.6
Appendix _______________________________________________________ 128
13.7
References ______________________________________________________ 129
14 Errors in Experimental Physics ____________________________________ 130
14.1
Introduction ____________________________________________________ 130
14.2
Sources of error in Experimental Work ______________________________ 130
14.3
Graphs and Errors _______________________________________________ 134
14.4
SigmaPlot® _____________________________________________________ 136
14.5
The Combination of Errors ________________________________________ 138
14.6
SIGNIFICANT FIGURES AND DATA/ERROR PRESENTATION ______ 139
14.7
GENERAL EXPRESSIONS _______________________________________ 139
14.8
CONCLUDING COMMENTS _____________________________________ 140
15 Sigma Plot® Tutorial ____________________________________________ 141
15.1
ENTERING DATA INTO THE WORKSHEET ______________________ 141
15.2
FITTING THE DATA ____________________________________________ 141
15.3
PLOTTING THE DATA AND FIT _________________________________ 142
15.4
TRANSFORMING THE DATA ____________________________________ 142
16 The Safe use of Lasers ___________________________________________ 143
16.1
General Comments _______________________________________________ 143
16.2
PRECAUTIONS WITH LASERS __________________________________ 143