GENERAL INSTRUCTIONS

[Requirements | Grading | Lab Reports | Significant Figures ]

The laboratory is designed to give you experience with the physical applications of the theory you will receive in lecture and recitation, and to introduce you to some techniques of data analysis.

I. The requirements of the laboratory are as follows:

A. Attendance will be taken and is required for each lab period   If you miss a lab due to illness or other problem, you are still responsibile to make up the lab.  You need to arrange a lab make-up session by contacting the lab instructor. If you fail to make up a missed experiment, you will receive an incomplete for the course. .  It is the responsibility of the student to be aware of the University regulations regarding an Incomplete.

B. You will be required to make a brief report for each experiment. This report must be made individually by each student and will include the data taken during the experiments, calculated results, graphs, tables and any conclusion you arrive at as a result of performing the experiment.  The lab reports are to be turned in one week after the lab has been completed.  A late report or no report will result in a lowered grade.  A grade reduction of 5% per day for late reports will be made down to a score of  0% for that lab report.

C. You need to prepare for the experiments before lab time since you will be expected to know the main ideas of the theory and procedure. Each instruction sheet will contain a complete description of the experiment (usually with schematic diagrams and/or pictures) and the procedure. You should be able to recognize the equipment from the drawings and pictures in the write-up. A SHORT QUIZ OVER THE EXPERIMENT'S IDEAS AND/OR PROCEDURES MAY BE GIVEN IN CLASS.
Please bring your own calculators, graph paper, straight edges, etc.

II. The grading for the lab is as follows:

10% - Based on in class lab quizzes at the beginning of the lab.

10% - Based on in class data documentation (lab book)

10% - the instructors evaluation of  the preparation for the laboratory,
	  and the general understanding shown by the student for laboratory work.


70% - Based on the lab reports.

III. Lab Reports:
Lab reports are due one week after the completion of the experimental protion of the lab. An experiment is not complete until a report is turned in.  Reports should be turned in on time otherwise the grade will be reduced 5% per day for late reports. . Lab reports should be given to your instructor at the beginning of the class the day they are due.
You will need to purchase two lab book for this course. These will be used for both data documentation and the lab report. Mr. Long will have one that his is grading and the other you will use for the current experiment. Clearly state on the report section the report the experiment for which it pertains, along with your name, Physics 271L and the date and your lab partner's name.

Some Labs will require only an In Class Reports. these should be abbreviated versions of the full lab reports which follow the laboratory report outline given below.  Prudent time management is essential in order to complete the in class reports.  Although abbreviated, in class reports should include a sentence of purpose and procedure (a diagram or picture of the equipment and setup is often sufficient), and a concise analysis of the data, which should include a discussion of error, sufficient to compare and contrast with the expected results. 

You will often be using fairly expensive equipment. Be aware of this and have your lab instructor check your set-up before you start to work. Do not plug in circuits to the power supply until the circuits have been checked.

Physics 271L Laboratory Report Outline

1. Title Section: This includes Physics 271L, the experiment number and title, your name, your lab partner's name,  the date the experiment was performed and the date the report is being turned in.
2. Introduction: In your own words describe what it is that you are investigating in the experiment.
3. Procedure/Data: Before each set of measurements, briefly describe how the measurements were made. If you have to construct a circuit, include the diagram of the circuit. ORGANIZE your DATA neatly into tables with columns. USE A RULER!
4. Graphs/Calculations: For some data you may be asked to graph the data to obtain a straight line indicative of a particular theoretical relationship. On the graph include:
   • (i) A title.
   • (ii) labeled axes with units.
   • (iii) straight line (made by a ruler) axes.
   • (iv) data neatly plotted
   • (*v) slope of straight line with units.
   • (*vi) intercept straight line with units.
   • (vii) error bars on the data points.

   
   

   	*When calculating slope and intercept, it is acceptable 
   	to use the least squares fitting provided on many 
   	calculators. If you choose L.S. Fit,  then please 
   	indicate as such. Otherwise, calculate slope & 
   	intercept from your best line through your data points. 
   	DO NOT use a data point in your slope calculation, 
   	take points from your line.
   		

5. More Graphs/Calculations: Any manipulation of data involving anything more complex than a single multiplication, show first the symbolic manipulation and then substitute one pair of data points.
   example:

   

                                                       symmbolic manipulation          data points

6. Conclusion/discussion: When you have finished all of the above, then conclude the report.  What did you learn?  Does this confirm the theory?  What can be done to improve the experiment?  What is the error involved with these measurements?   What are the sources of error?
   

Significant Figures

When taking data, the numbers recorded and the calculations made with them are not known with unlimited precision. The term "significant figures" is used to indicate the precision to which a given number is known and includes all digits in that number which are known with certainty plus the first uncertain digit.

Rules for Determining Significant Figures

1. All non zero digits are significant.
2. All zeros between non zero digits are significant.
3. Zeros to the right of a non zero digit are significant ONLY if specifically indicated to be so or if they precede a decimal point.
           ex. 500 generally would be considered to have 1 significant figure.
4. All zeros to the right of a decimal point and which are not preceded by a non zero digit are not significant.
   
           ex. 0.03 has 1 significant figure.
   
                1.005 has 4 significant figures.
5. All zeros to the right of a decimal point and to the right of a non zero digit are significant.
   
           ex. 1.00 has 3 significant figures.
   
                 .050 has 2 significant figures.
6. Notation using powers of 10 may aid in noting the numbers of significant figures. This allows the placing of the decimal point according to the preceding rules. Combining rules 5 and 3, if 500 were given to 3 significant figures, one would write 5.00 x 10².   If it were known to 1 significant figure, it would be given as 5 x 10².

Operations Using Significant Figures and Propagation of Error

1. Addition and Subtraction
   The right most significant figure in a sum or difference occurs in the left most place at which a doubtful figure occurs for the measurements involved. The uncertainty in the sum or difference is the sum of the absolute values of the individual uncertainties.
   In this example, the result would be recorded as 119.4 ± .1, since the left most place in which a doubtful figure occurs in the first decimal place. The number must be rounded off to that digit. Usually rounding off consists in raising the last significant digit by 1 if the digit to its right is between 5 and 9, otherwise leaving it as it stands. Had the first number in the example been 3.90, the result of the example would have been 119.5 ± .1.
   
2. Multiplication and Division
   The product or quotient is known to the precision of the number of significant figures in the least precise factor. The uncertainty is the percentage equal to the sum of the individual percentage uncertainties.

   

3. Calculations involving polynomials and transcendental functions.
   If a quantity y has an uncertainty Dy, then the uncertainty in yⁿ is given by

   

   or

   .

   The uncertainty in lny is

   .

   The uncertainty in sin(y) is

   .

   These are approximations with y small compared to y.