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PHYSICSPROJECTLABPhysics Project LabPaul GluckJerusalem College of EngineeringJohn KingMassachusetts Institute of Technology33Great Clarendon Street, Oxford, OX2 6DP,United KingdomOxford University Press is a department of the University of Oxford.It furthers the Universitys objective of excellence in research, scholarship,and education by publishing worldwide. Oxford is a registered trade mark ofOxford University Press in the UK and in certain other countries Paul Gluck and John King 2015The moral rights of the authors have been assertedFirst Edition published in 2015Impression: 1All rights reserved. No part of this publication may be reproduced, stored ina retrieval system, or transmitted, in any form or by any means, without theprior permission in writing of Oxford University Press, or as expressly permittedby law, by licence or under terms agreed with the appropriate reprographicsrights organization. Enquiries concerning reproduction outside the scope of theabove should be sent to the Rights Department, Oxford University Press, at theaddress aboveYou must not circulate this work in any other formand you must impose this same condition on any acquirerPublished in the United States of America by Oxford University Press198 Madison Avenue, New York, NY 10016, United States of AmericaBritish Library Cataloguing in Publication DataData availableLibrary of Congress Control Number: 2014940248ISBN 9780198704577 (hbk.)ISBN 9780198704584 (pbk.)Printed and bound byCPI Group (UK) Ltd, Croydon, CR0 4YYLinks to third party websites are provided by Oxford in good faith andfor information only. Oxford disclaims any responsibility for the materialscontained in any third party website referenced in this work.This book is dedicated to the memory of my co-author Professor John King,a great physicist and educator and a ne, warm, human being.Paul GluckAcknowledgmentsWe are very grateful to Professors Charles Holbrow and Gabriel Spalding for their critical reading of the manuscript andmaking extremely useful suggestions which we adopted in the revised version.Special thanks are due to Jessica White, Victoria Mortimer, and Richard Hutchinson at Oxford University Press for allthe help and kindness extended to us throughout the process of publication.ContentsFigure acknowledgments xProjects: why and how? 1Part 1 Mechanics1 Bouncing balls 132 Mechanics of soft springs 173 Pulse speed in falling dominoes 254 A variable mass oscillator 285 Rotating vertical chain 346 Cycloidal paths 387 Physics of rubber bands and cords 448 Oscillation modes of a rod 49Part 2 Electromagnetism9 Physics of incandescent lamps 5710 Propulsion with a solenoid 6211 Magnetic dipoles 6912 The jumping ring of Elihu Thomson 7413 Microwaves in dielectrics I 8014 Microwaves in dielectrics II 8615 The Doppler effect 8916 Noise 9417 Johnson noise 10218 Network analogue for lattice dynamics 10619 Resistance networks 111viii ContentsPart 3 Acoustics20 Vibrating wires and strings 11721 Physics with loudspeakers 12422 Physics of the tuning fork 12923 Acoustic resonance in pipes 13424 Acoustic cavity resonators and lters 13825 Room acoustics 14126 Musical instruments: the violin 14627 Musical instruments: the guitar 15128 Brass musical instruments 155Part 4 Liquids29 Sound from gas bubbles in a liquid 16330 Shape and path of air bubbles in a liquid 16831 Ink diffusion in water 17332 Refractive index gradients 17633 Light scattering by surface ripples 18034 Diffraction of light by ultrasonic waves in liquids 18435 The circular hydraulic jump 18836 Vortex physics 19237 Plastic bottle oscillator 19738 Salt water oscillator 201Part 5 Optics39 Birefringence in cellulose tapes 20740 Barrier penetration 21241 Reection and transmission of light 21542 Polarization by transmission 22143 Laser speckle 226Contents ix44 Light scattering from suspensions 23245 Light intensity from a line source 23646 Light interference in reecting tubes 239Part 6 Temperature and Heat47 Cooling I 24548 Cooling II 24849 The Leidenfrost effect I 25450 The Leidenfrost effect II: drop oscillations 25851 The drinking bird 26052 Liquidvapor equilibrium 26653 Solar radiation ux 270Appendix A: Project ideas 273Appendix B: Facilities, materials, devices, and instruments 290Appendix C: Reference library 310Index 315Figure acknowledgmentsExplanation of gure acknowledgments:4.4, 4.5: 71, 721(2003) means Figures 4.4 and 4.5 in the text, followed by the journal reference (volume number, pagenumber, publication year).Figures in the text reproduced with permission fromjournals published by the American Institute of Physics, by permissionof the American Association of Physics Teachers:American Journal of Physics:4.4, 4.5: 71, 721(2003); 11.4: 62, 702(1994); 13.2: 48, 648(1980); 13.4: 54, 712(1986); 13.5: 52, 214(1984); 14.2:45, 88(1977); 20.2: 53, 479(1985); 35.3: 67, 723(1999); 36.2, 36.4: 75, 1092(2007); 37.5: 75, 893(2007); 39.4: 41,1184(1973); 40.3: 43, 107(1975); 41.4: 50, 158(1982); 45.2: 63, 47(1995); 48.2: 61, 568(1993); 52.2: 64, 1165(1996).The Physics Teacher:9.2: 45, 466(2008); 23.2, 23.3: 44, 10(2006).Physics of Fluids A:30.2: 14, L49(2002).Figures in the text reproduced from journals published by the Institute of Physics UK, by permission of IOP Publishing:Physics Education:1.4: 33, 174(1998); 1.5: 33, 236(1998); 2.9: 45, 178(2010); 6.66.11: 45, 176(2010); 10.3, 10.4, 10.9: 45, 466(2008);12.7: 7, 238(1972); 28.1, 28.2, 28.3: 38, 300(2003).European Journal of Physics:18.7: 1, 129(1980); 29.3, 29.4: 8, 98(1987); 21, 571(2000); 44.3: 7, 259(1986); 46.3: 13, 47(1992); 48.3, 48.4, 48.5: 30,559(2009).Projects: why and how?Introduction 1What is a project? 2Overcoming the fear 4Tools of the trade 5Researchers, choices, and the toil 7Is it worth the effort? 9About the book 9IntroductionThis book is intended for our colleagues, teachers of physics at universities andcolleges, and their students. While signicant reference is made to material typic-ally encountered beyond the rst year of university-level study, high school teachersand their students may also nd many opportunities here. Like us, many readershaveprobablybeenteachingphysicsmostoftheirlivesinwhatmaybecalledtransmission mode, that is, instruction by means of textbooklessonrecitationlaboratory.Inthismodewe,theteachers,send,andourcharges,thestudents,receiveinformationandskills,inconformitywithJohnLockesnotionthatthestudents mind resembles an empty slate to be written on.But there is another mode of instruction, exemplied by what Rousseau wrotein his book Emile: Teach by doing whenever you can, and only fall back on wordswhen doing is out of the question. We may call this the transformation mode.Now, both teacher and student are transformed into explorers, with benets toboth. Fortheteachersinaresearch-basedinstitutionnothingshouldbemorenatural than to carry over the research style into some of their teaching activity.Why this does not happen more often deserves serious discussion. For teachers ina high school it is an opportunity to partake in and guide research, and this couldprove to be the activity that relieves repetition and lifts them from the rut. For thestudent it is a chance to experience the way science works.An important aspect of the project lab is that the teacher, though generally ex-perienced, doesnt always know the answers to the questions raised in the projectany more than the students do. So much so that instead of the words teacher andstudent we will use guide and researcher. (Except when we quote.)The two modes of learning should be combined in a proportion that suits thepersonalities of guides and researchers alike. It is not our aim in this book to evalu-ate the competing modes. The research literature in physics teaching in the past30 years has been devoted to that, and it behooves us to be mindful of it. Rather,we should like to extend an invitation to the reader to try something different, atleast as far as laboratory work is concerned, namely, to teach physics by guidingresearchers through projects. It may happen that once tried, the experience willbe habitforming, and thatshall be ourreward forwriting thisbook.For thoseof our readers who have guided projects for years these remarks are like preach-ing to the converted. We hope that for them this book will be a source of furtherideas.2 Physics Project LabWhat is a project?GregLockett, ateacherwhoparticipatedintheLabNetprojecthasdescribedimportant aspects of project lab [1]:Thegoal of theguideistore-createtheprocessandexperienceofworking in the physics laboratory. Several features are important in thisapproach. Students are free to choose a research problem. They do notknow the solution to their problem at the outset. While they work withinthe constraint of time, resources and their current knowledge, they aregiven sufcient time and freedom to attack their problem as they see t.Collaborationisacceptableanddesirable.Theendproductcanvary:reports, papers, equipment, experiments, models, etc.In this process the goal is to give the student an immediate insideviewof howphysics is done. The teacher functions as a facilitator, some-what like a research director in a laboratory: obtains needed resourcesor suggests alternatives, resolves disputes about equipment schedul-ing and squabbles between partners, attempts to foster new ideas andtechniques, and strengthens theory when needed.Skills are learned as needed. These include guided journal, book andInternet searches, motor skills in building apparatus, social skills of col-laboration, communicationskills(oral, writing, optimal presentation),andmathematicalandanalyticalskills.Theprojectwilldemandthesenaturally, so problems of motivation will not arise.We would also like to quote two people involved in experimental physics whodescribe what we feel ought to be the approach to doing projects; namely, thatthe researcher should acquire the beginnings of various skills that were once es-sential inexperimental physics.Althoughinrecentdecadesdigita