Description of Apparatus
Drawing or Sketch
Step-by-step procedure (written in past tense)
NOTE: Steps 2a through 2e are included in the specific handout instructions for each lab experiment. Items 2.a. through 2.e. are including in the handout instructions for each lab experiment. Use the information in these instructions to rewrite Items 2.a. through 2.e., making sure you use the past tense for the Procedure (Tell how the experiment was performed. The handout tells how to perform the experiment).
Presentation of Results: In almost all cases, the presentation of results will involve tables, sample calculations and graphs. The proper sequence is as follows:
i. Recorded Data Table
1. Tables should be vertical with the variable listed at the top with its
appropriate units. You must initially list variables exactly as you recorded them, before any conversions. Variables should be spelled out completely (i.e. Temperature, not Temp.; Viscosity, not Vis.). Units may be abbreviated. The abscissa (independent variable) should be in the first column of the table with the ordinates (dependent variables) in the succeeding columns. If a second table for calculated and theoretical data is used, the abscissa must again be listed first, even if no calculations were performed on that variable. The final table should always contain those values which are being graphed so direct correlations may be made from the table to the graph(s).
ii. Sample Calculations
1. For sample calculations, show a complete set of calculations for a sample data point, preferably one near the middle of the data set.
iii. Calculated Data Table
1. If the data range is small you may include recorded and calculated data in the same table followed by sample calculations and then graphs.
1. It will be impossible to earn an “A” or “B” in this course unless computer graphing methods are used. Use a full page for each graph, with the graph taking up most of the page. Most graphing software does an excellent job of plotting the points, but draws straight lines from point to point. This is unacceptable. We are dealing with experimental data (not perfect data) and the values between points are important. If you are not using sophisticated software that does a good job of curve fitting, then you should allow the computer to plot the points and then you should draw a “best-fit”, smooth curve using a French curve, “cheater”, straight edge or a combination of these methods. A “best-fit” curve may touch all points or may not touch any points at all. It will usually have, alternately, as many points on one side of the curve as the other. The origin (0,0) of the graph may or may not be an important part of the curve. The inclusion of the origin on a curve will depend upon the type of experiment performed.
a. All graphs will be computer generated.
b. Place perceived binder holes at the left or the top of the graph.
c. Use workable scales that allow visual interpretation for those reading the graph (i.e. ,10,20,30,40,etc or 2,4,6,8,etc, not 7,14,21, 28 ,etc). Unless otherwise noted, all scales should be linear, starting at 0 and increasing from left to right or bottom to top. Do NOT let the computer dictate the scales; it may produce a scale with equal distances between points instead of a linear scale. There are two orientations that your graph may have in the report. Standard (vertical) orientation: the graph reads the like the text of the report with binder holes to the left side of the paper. Horizontal orientation: the graph is rotated 90 degrees clockwise so that the binder holes are located at the top of the paper. Either is acceptable. Choose one that allows you to draw the largest graph with workable scales.
d Include a Graph Title pertaining to the information presented.
e A legend should also be provided if more than one curve is drawn in order to show which symbol corresponds to which variable. There should also be a coordinate system clearly labeled on the graph. There will always be only one abscissa, but there may be more than one ordinate. For modified ordinates you may try to use the same relative scale for each by listing one variable multiplied by a factor of 10. For instance, suppose you are plotting pressure head and efficiency versus flow rate. Pressure head varies between 0 and 9, while efficiency is between 0 and 60. You could make one ordinate scale from 0-100 and then list the pressure head coordinate as Pressure Head X 10. This allows you to use one scale for two separate variables. Most software will allow at least two different ordinate scales. Make sure you title and specify units of coordinates (as you did in your tables—Pressure (psig)).
f. Label each axis including units [Pressure (psig)].
g. Vary the symbols used for data points if more than one curve is generated [ex: Circles for Pressure and Squares for Velocity].
i. Symbols should be used around all experimental points so they are not absorbed by the curve. Symbols may be used around theoretical points, but are not essential since theoretical data is more exact. If more than one curve is plotted on the same graph, then different symbols must be used for each curve. Colored curves enhance the presentation of data, but should not be used to replace symbols, since the colors may not photocopy.
ii. Ensure all graphs are clear and visible.
v. Discussion of Results and Conclusions
1. Discussions should be at least one-half a page, single spaced. The most important portion of this section is to discuss the curves you obtained. You should discuss the curve trend (increasing, decreasing, etc.), shape (linear, decreasing slope, etc.), irregularity (hump, erroneous point that is neglected, etc.), how the best fit curve fits the data points, and include comparisons to other experimental or theoretical curves. Some experiment handouts may have questions that you are to answer in your discussion. Please include these. Describe any problems with the experiment and suggest improvements. Conclude by listing any reasons you may have for your experimental results. Be sure to include the following in your discussion:
a. What did the results (curves) show you? (trend?, shape?, irregularity?) If appropriate, compare experimental to theoretical curves.
b. What are the reasons for your results (theory or deviations from theory?)
c. What problems were encountered during the experiment and suggested improvements?
d. Discussion should be written in clear and proper English.
e. Written in past tense using third person (ex: “The data indicated a linear relationship between…”).