Practical Physics

by G. L. Squires

• ISBN13: 9780521779401
• ISBN10: 0521779405
• Edition: 4th
• Format: Paperback
• Copyright: 2001-09-24
• Publisher: Cambridge University Press

Summary

This classic companion to undergraduate practical work in physics describes the purposeful, critical approach that should be made to all physics experiments. It covers the statistical treatment of data and experimental methods, and gives advice on keeping efficient records, calculations, and scientific writing. The new edition features treatment of the c2 distribution, a section on atomic clocks, worked examples based on spreadsheets, and additional exercises. Existing examples and references have been brought up to date. The text is liberally illustrated with examples and exercises, with solutions to the latter. Although intended for undergraduates, Practical Physics will be of interest to researchers, not only in physics, but in other sciences as well.

Author Biography

Gordon Squires has been a Lecturer in Physics at the University of Cambridge and a Fellow of Trinity College, Cambridge since 1956

Table of Contents

Preface to the fourth edition	ix
Preface to the first edition	x
The object of practical physics	1	(4)
PART 1 STATISTICAL TREATMENT OF DATA
Introduction to errors	5	(4)
The importance of estimating errors	5	(1)
Systematic and random errors	6	(2)
Systematic errors	8	(1)
Treatment of a single variable	9	(18)
Introduction	9	(1)
Set of measurements	10	(1)
Distribution of measurements	10	(4)
Estimation of σ and σm	14	(4)
The Gaussian distribution	18	(1)
The integral function	19	(3)
The error in the error	22	(1)
Discussion of the Gaussian distribution	22	(5)
Summary of symbols, nomenclature, and important formulae	24	(2)
Exercises	26	(1)
Further topics in statistical theory	27	(16)
The treatment of functions	27	(3)
The straight line - method of least squares	30	(6)
The straight line - points in pairs	36	(1)
Weighting of results	37	(6)
Summary of equations for the best straight line by the method of least squares	39	(2)
Exercises	41	(2)
Common sense in errors	43	(12)
Error calculations in practice	43	(3)
Complicated functions	46	(2)
Errors and experimental procedure	48	(7)
Summary of treatment of errors	50	(1)
Exercises	51	(4)
PART 2 EXPERIMENTAL METHODS
Some laboratory instruments and methods	55	(18)
Introduction	55	(1)
Metre rule	55	(2)
Micrometer screw gauge	57	(1)
Measurement of length - choice of method	58	(3)
Measurement of length - temperature effect	61	(1)
The beat method of measuring frequency	62	(2)
Negative feedback amplifier	64	(3)
Servo systems	67	(2)
Natural limits of measurement	69	(4)
Exercises	71	(2)
Some experimental techniques	73	(29)
Rayleigh refractometer	73	(6)
Measurement of resistivity	79	(7)
Absolute measurement of the acceleration due to the Earth's gravity	86	(8)
Measurement of frequency and time	94	(4)
The Global Positioning System	98	(4)
Exercises	101	(1)
Experimental logic	102	(15)
Introduction	102	(1)
Apparent symmetry in apparatus	102	(1)
Sequence of measurements	103	(1)
Intentional and unintentional changes	104	(1)
Drift	105	(1)
Systematic variations	106	(3)
Calculated and empirical corrections	109	(2)
Relative methods	111	(2)
Null methods	113	(1)
Why make precise measurements?	114	(3)
Common sense in experiments	117	(8)
Preliminary experiment	117	(1)
Checking the obvious	118	(1)
Personal errors	119	(1)
Repetition of measurements	119	(2)
Working out results	121	(1)
Design of apparatus	122	(3)
PART 3 RECORD AND CALCULATIONS
Record of the experiment	125	(8)
Introduction	125	(1)
Bound notebook versus loose-leaf	125	(1)
Recording measurements	126	(1)
Down with copying	126	(1)
Diagrams	127	(2)
Tables	129	(1)
Aids to clarity	130	(1)
Some common faults - ambiguity and vagueness	131	(2)
Graphs	133	(11)
The use of graphs	133	(4)
Choice of ruling	137	(1)
Scale	137	(1)
Units	138	(1)
Some hints on drawing graphs	138	(3)
Indicating errors	141	(1)
Sensitivity	142	(2)
Arithmetic	144	(8)
Arithmetic is important	144	(1)
Computers	144	(1)
Calculators	145	(1)
Ways of reducing arithmetical mistakes	145	(3)
Checking algebra	148	(4)
Exercises	150	(2)
Writing a paper	152	(44)
Introduction	152	(1)
Title	152	(1)
Abstract	152	(1)
Plan of paper	153	(1)
Sections of paper	153	(2)
Diagrams, graphs, and tables	155	(1)
Instructions to authors	155	(1)
Clarity	156	(1)
Good English	156	(2)
Conclusion	158	(3)
Appendices
A Evaluation of some integrals connected with the Gaussian function	161	(3)
B The variance of S2 for a Gaussian distribution	164	(2)
C The straight line - the standard error in the slope and intercept	166	(5)
Comment on the dependence of m, c, and b	170	(1)
D The binomial and Poisson distributions	171	(5)
Binomial distribution	171	(2)
Poisson distribution	173	(3)
E The X2 distribution - test of goodness of fit	176	(12)
Introduction	176	(1)
Derivation of X2 distribution	177	(3)
The function Pn(X2)	180	(1)
Degrees of freedom	181	(1)
Test of goodnes of fit	182	(2)
Worked examples	184	(2)
Comments	186	(2)
F SI units	188	(4)
Names and symbols	189	(1)
Decimal factors	190	(1)
Relation to c.g.s. units	190	(1)
Definitions of the SI base units	191	(1)
G Values of physical constants	192	(1)
H Mathematical tables	193	(3)
Values of the Gaussian function and the Gaussian integral function	193	(1)
Values of X2 for given v and P	194	(2)
Solutions to exercises	196	(10)
Some useful books	206	(1)
References	207	(2)
Index	209