The CBL is a portable, handheld, battery-operated, data collection
device for collecting "real world" data. The data collected
with the CBL can be retrieved by TI-82/83/85 graphing calculators
for analysis. With the CBL system and appropriate sensors, you
can measure motion, temperature, light intensity, sound intensity,
pH, force, and more. Probes, or sensors, provide the means by
which data is collected or sensed. In addition to the three probes
provided (temperature, light intensity, voltage), many existing
third-party probes such as ultrasonic motions detectors, force
probes, pH sensors, etc. can be used with the CBL system when
connected with optional adapters.
In this activity you will familiarize yourself with the CBL System
by completing two (2) directed experiments which you will write
up in a more formal way. You may need assistance in locating some
of the materials for these activities. See your course instructor
for assistance.
1. Complete activities D1 and D2 before you begin this project.
2. Obtain and familiarize yourself with the CBL, its sensors, adapters, and the System Workbook. Contact your course instructor for access to these materials.
3. Perform ONE directed experiments found in the CBL System Experiment Workbook folder, each time using a different sensor probe. (Additional probes besides those that originally came with the CBL unit are available.) The experiment should be chosen from the section entitled, "Exploring Physics with the CBL." Give due attention to calibrating your probes if necessary. Use a graphing calculator to graph and perform a statistical regression of you data. Print out the data screens. Create and print out all required graphs and regression relations using Graphical Analysis. Read the Graphical Analysis handbook to determine how to import data from the TI-82/83/85 calculator if necessary. Answer all questions found in the body of the Experiment Workbook exercises, and fully analyze the data you collect. Print your graphs, along with regression equation and data, using Graphical Analysis.
4. Write a high-school-level laboratory report for the activity using the following guidelines taken directly from the course instructor's University High School physics course syllabus:
Each lab report will consist of a cover sheet or sheets, data sheet(s), graph(s), and an analysis sheet on which sample calculations are shown. These must be assembled in the same order and stapled together before turning in. Lab reports are due at the end of the time period in which these exercise sets are required to be completed.
The cover sheet will contain student name, laboratory name, and date of exercise. On this cover sheet you will write a brief summary. The summary should address the four following items: 1) the purpose of the lab experiment (That is, what you accomplished in this exercise. For example, "In this experiment I verified Snell's law." or "In this experiment I confirmed the value of the acceleration due to gravity."), 2) a short statement of your findings, 3) a short summary of the procedure you followed, 4) what degree of accuracy you were able to achieve in your work (For example, "I verified that the angle of incidence equals the angle of reflection to within an experimental accuracy of 2%." or "I showed that Ohm's law is valid to within an experimental accuracy of 0.3%."), and 5) what the possible sources of error were (i.e., "The error in the result arises from an inability to accurately measure..."). This write-up should be done using complete sentences. The cover sheet must be type written (word processed). GRAMMAR COUNTS!
DATA SHEET(S):
Each lab report must include the original data sheet(s), which you will find in the lab handout. Data tables should be neat and orderly with no calculations or extraneous notation. Data should be recorded using pencil. All erasures must be neat and clean.
GRAPH(S):
If graphs are required, they must be included as part of the lab report. Prepare one per page using only one side of each sheet of ruled paper. Choose the limits or scale the axes so your graph fills the entire page.
Label each graph with a title. Label and give units on each of the graph's axes. [for example: velocity (meters/second)]. The appropriate smooth curve should be drawn representing the function graphed. UNDER NO CIRCUMSTANCES SHOULD YOU CONNECT THE DATA POINTS WITH A SERIES OF STRAIGHT LINES.
If the graph of data points is a straight line, then determine the slope and write the approximate equation in your analysis sheet. If the graph is not a straight line, then you must attempt to linearize the data.
ANALYSIS SHEET:
The analysis sheet is a coherent and well-ordered presentation of sample calculations made as part of the experiment. Show all employed equations as part of your sample calculations. Your calculations must carry units throughout. Calculations must reflect an understanding of significant digits. Do a sample of each calculation performed in the experiment. Trivial calculations such as addition, subtraction, and averaging need not be included.
If you are calculating the slope of a graph line, be sure to include these calculations in your analysis. Note that the slope usually has units and a physical meaning. These must be included in your analysis. Do not perform calculations on the data sheet or graphs.
Prepare your analysis sheet using the same logical order in which the experiment was performed. If the analysis steps are written in order and numbered, this means you should number items in your analysis sheet in the same fashion. Perform all analyses that are indicated in your lab manual or by your lab instructor.
ACCURACY OF RESULTS:
Each student's work should reflect the fact that care was taken in all measurement processes. Though the accuracy of your results will vary from experiment to experiment, overall error should be relatively small throughout.
If a result departs markedly from the anticipated result (as indicated by a large margin of error), a follow-up set of measurements should be made to isolate and eliminate the source(s) of error.
The integrity of the data must be preserved at all times. In no case should the student skew the data so that proper experimental results or a smaller experimental error are achieved.
Use the following definitions of % difference and % error:
Percent Error An indication of how far off your experimental value is from the officially accepted value; the difference divided by the accepted value expressed in a percentage form.
% error = | experimental value - accepted value | x 100 / accepted value
Percent Difference An indication of how far off one experimental value is from another experimental value; the absolute difference divided by the average expressed in a percentage form.
% difference = | A - B | x 200 / (A + B)
where A and B are experimental values.
The student's efforts will be assessed on the basis of the written laboratory
reports. The lab report will be worth five (5) points.