Introduction It's useful to spend a few minutes at the start of the semester thinking about your expectations for the laboratory part of your introductory physics course. The course will be more beneficial to you, and you will feel more satisfied with your work, if you understand its purposes. In other words, what should you expect to get for all the time spent on your lab course besides a measly 10% of your course grade? The major objectives of the introductory physics laboratory are listed below, not necessarily in their order of importance. Each experiment that you do will address some of these objectives, but the priorities will vary from week to week. I Verification Physics undergraduate teaching labs have traditionally offered the student an opportunity to observe phenomena that demonstrate basic principles. You will operate simple apparatus, take notes and form conclusions based on patterns found in the data. If the lab is well conceived, you will find for yourself that this or that physical law is obeyed. Verification is an important part of the physics lab experience. You will not discover new laws, but you will check them for yourself. II Training The lab should in some way begin to teach you to be a scientist. The lab experience should teach techniques and develop skills. Physics labs employ scientific techniques of many kinds; there are measurement procedures, data reduction strategies, and measurement error assessments. You will be introduced to methods similar to those used in research labs. Closely associated with technique is a more intangible concept, skill. This refers to such mental attitudes as inquisitiveness, imagination, objectivity, and skepticism, together with such personality traits as competitiveness, endurance, perseverance, and the ability to trouble-shoot and to organize resources including time and effort. The Physics department hopes you will come to appreciate the style of a research scientist: self-directed, confident, cautious, unassuming, and clear thinking. III Alternative learning environment The laboratory offers an opportunity to learn some topics which are not discussed in the lecture part of the course. In some instances this means the lab will be your only exposure to certain standard physics topics which may not even be discussed in your textbook. Mostly this means that the lab course offers you the opportunity to develop skills that you will need later, but which do not fit easily into the lecture part of the physics course. The skills listed in the previous paragraph are among these. Two other important areas, discussed below, are computer literacyand technical writing. Measurement Physics is a quantitative science. This means that experimental physicists organize observations by identifying quantities which they measure. Measurements are assigned numerical values. A responsible experimenter also assesses the reliability of the numerical result. In planning an experiment one first begins by thinking carefully about what quantities to measure. Physics experiments are expensive to construct and carry out. It is usually not practical to begin an experiment before one has a very good estimate about the eventual outcome. That is, one must rely on previous experimental work or on a theoretical model to predict the size of the quantity to be measured. He must also think about how precisely the quantity must be measured in order that the results be meaningful. These two considerations then lead one to choose the appropriate techniques and to estimate the cost and time required to complete the work. Planning requires prior experience, of course, so introductory physics labs are planned by the teaching staff, not by the student. Computers The most common research tool is the digital computer. Computers are used in all phases of an experiment: planning, execution, and data reduction. The physics laboratory is an excellent place to learn about computers. We use an inexpensive microcomputer which is, nevertheless, capable of doing all the kinds of things that newer, faster, more powerful computers do in research labs. The kinds of planning mentioned above often involve writing a program which simulates the behavior of the apparatus. The computer is taught the appropriate physical laws, and the principles by which the equipment is to be designed. The parameters which define the equipment are the input to the program, and the physical quantity to be measured is the output. The program is run with different realistic inputs until the desired output is obtained. A carefully designed simulation is a very reliable guide to the design, not only of equipment, but of experimental procedures as well. Modern experiments usually measure voltages or count occurrences of an event. That is, there is some device which converts the physical quantity of interest (position, force, etc.) into an electrical signal. Computers can measure voltages accurately. They are also fast, and they don’t mind doing repetitive tasks, whose tedium might otherwise lead a bored scientist to make sloppy mistakes. An experiment usually seeks to determine how the value of one physical quantity depends upon the value of some other physical quantity. The latter, or “independent” quantity can be set by having the computer send an electrical signal out to the apparatus. The ability of the computer to both set and measure voltages gives it the power to conduct experiments with little attention paid by the experimenter. The computer can, of course, be programmed to record all the results in a “notebook”, usually a magnetic storage medium. Often it is not feasible (or even possible) to directly measure the quantity of interest. The experimentalist uses her imagination to find a related quantity which she can measure and which she can unambiguously relate to the quantity of interest. An example is the measurement of successive positions of a moving body from which one can determine its acceleration. The computer is taught the (sometimes very complex) relation between the measured quantity and the desired quantity, and how to extract the desired quantity from the data. This process, known as “data reduction”, also includes relating the accuracy of the derived quantity to the inherent accuracy of the measurement itself. Finally, the reduced data must be compared with the model which is being investigated. Again, this can be, in some instances, a mathematically tedious process. The computer can be programmed to carry out this “data analysis” as well. Writing Experimental results are of no value unless they are communicated to the larger scientific and technological community. The scientific literature is the repository of results which are written up and published. The introductory lab experience teaches you how to use scientific terms correctly and how to present results in written form. Your handout contains guidelines for reporting student lab results, which you will write up and submit for grading.   IV Rewards The introductory physics laboratory experience is quite broad. The rewards go far beyond “a measly 10% of your course grade”. In addition to the intellectual satisfaction of seeing for yourself the validity of some basic physical laws, you will acquire techniques and skills that are part of the qualifications needed to become a working scientist. These are things which cannot be effectively taught in a lecture course alone.