Physics 53 Elect!city and Optics Laboratory Course Manual Fall 2005 In"ructors T. Donnelly J. Eckert D. Hoard T. Lynn G. Lyzenga P. Saeta Joseph von Fraunhofer Carl Friedrich Gauss Gustav Kirchhoff “Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Per- sistence and determination alone are omnipotent.” Calvin Coolidge Contents I Introductory Material iii Quick Start Guide for First Meetings 1 Schedule 2 Overview 3 General Instructions 6 Philosophical Musings 9 II Experiments 11 1 Basic DC Circuits 12 1.1 Overview . 12 1.2 Theory . 12 1.3 Precautions . 13 1.4 Procedure.................................................... 14 1.4.1 Resistors in series . 14 1.4.2 Resistors in parallel . 14 1.4.3 Circuit loading . 15 1.4.4 Charge and discharge of a capacitor in an RC circuit (optional) . 15 2 Absolute Current 16 2.1 Overview . 16 2.2 Background . 16 2.3 Theory . 18 2.4 Experimental Equipment and Procedures . 20 2.4.1 Preliminary setup . 20 2.4.2 The Current coil . 20 2.4.3 Compass deflection measurements . 21 2.4.4 The Bar magnet and torsional oscillations . 21 2.5 Experimental Analysis . 22 2.5.1 Fitting . 22 3 RLC Resonance 24 3.1 Overview . 24 3.2 Theory . 25 3.2.1 AC voltages as complex numbers . 25 3.2.2 Complex impedance . 26 3.3 Experimental Procedure . 27 3.3.1 Equipment and software . 27 4 Geometrical Optics 32 4.1 Overview . 32 4.2 Background and Theory — Refraction . 33 4.3 Experimental Procedures — Refraction . 33 4.3.1 Measurements . 34 4.3.2 Analysis . 34 i CONTENTS CONTENTS 4.4 Background and Theory — Lenses . 34 4.4.1 Diverging lens . 36 4.5 Expt. Proc. — Image Formation . 37 4.5.1 Preliminaries . 37 4.5.2 Converging lens . 38 4.5.3 Diverging lens . 39 4.5.4 Chromatic aberration . 39 4.5.5 Depth of field . 39 5 Fraunhofer Diffraction 40 5.1 Overview . 40 5.2 Background and Theory . 40 5.2.1 Single slit . 41 5.2.2 Double slit . 41 5.2.3 Multiple slits . 42 5.3 Experimental Procedures . 42 5.3.1 Alignment procedure and preliminary observations . 42 5.3.2 Removing the photocell mount . 43 5.3.3 Potentiometer . 44 5.3.4 Beam profile . 44 5.3.5 Taking data . 45 5.3.6 Program details . 46 5.3.7 Saved data . 46 6 Grating Spectrometer 47 6.1 Overview . 47 6.2 Theory . 47 6.3 Using the Spectrometer . 49 6.3.1 Focusing procedure . 49 6.4 Experimental Measurements . 51 6.4.1 Grating calibration . 51 6.4.2 Hydrogen observations . 52 6.4.3 Forensic investigation . 52 6.5 Experimental Analysis . 52 III Appendices 54 A Electric Shock – it’s the Current that Kills 55 B Resistors and Resistance Measurements 57 C Electrical Techniques and Diagrams 59 D Technical Report 60 Physics 53 Lab Manual ii July 22, 2005 Part I Introductory Material iii Quick Start Guide for First Meetings The following is a brief summary of the essential in- require advance reading and preparation! It is very formation you’ll need to prepare for the first meetings important that you come to the lab prepared. Be- of E&M Lab. Further details will be found elsewhere fore the first laboratory meeting for a particular ex- in this manual and in the other resources provided to periment, read the appropriate section of this lab man- you by the instructors. ual and watch the short movie introducing the exper- iment you will be doing. The movies are available at First Meeting the course web site: http://www.physics.hmc.edu/ courses/p053/. We will not require pre-lab homework The first meetings of each lab section will be dur- or exercises; however, part of your grade will be based ing the week of Aug. 29 (except for Monday sections on your instructor’s assessment of how prepared you are which will first meet on Sept. 5). The sections will then for lab. meet on succeeding weeks for two hours throughout the The semester schedule has built-in days off from lab semester, following the schedule of meetings and breaks meetings, so please take advantage of this in managing on the following page. Although it is not heavy, there your time, and remember to budget time for lab prepa- is some preparation for the first meeting. In the first ration. The lab periods run for 2 hours every meeting, meeting there will be a brief orientation by the instruc- and each experiment (except #1) will take two lab pe- tor to all the experiments, with related discussions of riods. The first week (meeting “a”) will typically be methods of data analysis. You will then perform Exper- useful for familiarizing yourself with and calibrating the iment 1, which is an introduction to simple DC electri- apparatus and making a first set of measurements; the cal circuits. Prior to coming to lab, you must read the second week (meeting “b”) will normally be used for lab manual introduction and description for Experi- completion of data taking, recovery from any problems ment 1 (pp. 1–15). Also come to lab prepared with or mistakes in the first week, and consultation with your a brown cover National Brand #43-648 Computation instructor about analysis and write-up. Notebook (available from the bookstore). Experiment 1 is shorter and simpler than the other experiments in Write-up of the Experiment the course, so you should be able to complete it in the abbreviated time available and experience a relatively A typical experiment summary is 2–3 typed pages, easy “warm-up” for the later lab activities. turned in along with your lab notebook for documen- tary support, at a time and place to be announced by Plotting Exercise each instructor. All write-ups should be typed/word processed, with all graphics neatly and professionally In this course, everyone will be responsible for be- incorporated. An example is available on the course ing fluent in a data plotting/fitting software pack- web site. The experiment summary will be what is pri- age. To help reinforce this, everyone is required to marily read and marked by your instructor. The lab complete and turn in a data plotting exercise. As book may not be graded in detail, however the degree soon as possible (but before your #2a meeting) go to which it serves as a valid reproducible archival record to the web page at http://www.physics.hmc.edu/ of your work in lab will form a part of your grade. In the analysis/exercise.php and complete the exercise. write-up, you may assume your reader is familiar with Turn in the finished plot to your instructor. your experiment, the apparatus, and.