Examples of Lab Report Cover Sheets

Examples are given below showing both a poor lab reportand a good lab report. The sections in regular type are the reports themselves. Sections in italics are the grading comments and hintsfor writing better reports.

Student A

Name:____Student A_______ Partners:______________________________
Title:____Finding the Density of Copper_______
Date Performed:____7/8____ Date Submitted:____7/10____
Section:____2701____TA:_______________

Purpose:

The density of copper was found using a method similar to that used by Archimedes. Todetermine whether or not a corwn was gold. The mass was divided by volumes measured in twoways. (1) The length and radius of the cylinder were measured and the volume was calculatedusing V = (pi)(r^2)L. (2) The cylinder was dropped into a full beaker of water and the volume ofoverflow was measured with a graduate cylinder.
  1. Irrelevant historical material.
  2. Do not copy the procedure from the lab manual.
  3. Save the equations for the sample calculation section.
  4. Be careful about spelling and correct terminology!

Results:

Our error was due to five things:
  1. The old weights were probably inaccurate because they were old.
  2. The temperature and barometric pressure of the room might have been changed, affectingthe density of both copper and water.
  3. While the scale was being used there may have been variations of a slight earthquake or achange in gravity.
  4. We mignt have read the vernier incorrectly.
  5. Maybe we should have counted the hook.
    1. Do NOT use first person pronouns.
    2. The numerical values of the density of copper and their associated experimental error shouldhave been given. Save any commentary for the discussion section.
    3. Mights and maybes should be replaced with measurements or reasonable quantitativeestimates of the changing quantities.
    4. #4 was a mistake in a procedure, not an experimental error which denotes the uncertainty ina measurement. Seek clarification of procedures while in the lab so that you can obtain the bestdata possible.
    5. #2 could have been a nice quantitative evaluation if the statement had been supported by aquantitative comparison.
    6. #3 is absurd. If you can't see the scale vibrate, it doesn't. The acceleration of gravitychanges with altitude, not time.
    7. #5 is very vague. Be specific about why you think you should have included the hook. Include the affect of including the hood - would including it have made your measurement of thedensity larger or smaller than the value you calculated without it.

Discussion:

By the same methods we could have measured iron, nickel, or any other metal or even apiece of rock. Instead of water we could use oil, alcohol, or any liquid. Our percent of error was1% and was probably due to bad equipment. We should have been given a micrometer and abetter scale so that the measurements could be done accurately.
  1. Make sure that any suggestions on improvements or extensions to the experiment are notthis obvious or trivial.
  2. The second paragraph could have been a good quantitative discussion if pursued. Comments could have included the limitations of particular measuring tools and the affect ofchanging those tools.

Student B

Name:____Student B____ Partners:______________________________
Title:____Finding the Density of Copper_____
Date Performed:____7/8____ Date Submitted:____7/15____
Section:____2701____ TA:____P. Sabes____

Procedure:

Measurements were made of the density of copper by dividing the measured mass by avolume either calculated from the measured dimensions of the cylinder or by volumedisplacement. Good, inclusive statement of the goal and methods for thisexperiment.

Results:

Accepted value: Density = 8.93 g/cm3Experimental uncertainty = 1.8%
Procedure #1: Density = 8.83+-0.04 g/cm3 (STD)% Error = 1.1%
Procedure #2: Density = 8.79+-0.16 g/cm3(STD)% Error = 1.6%
  1. Good, lists relevant results. (They should match the goal listed in the Purposestatement.)The measured values include the relevant uncertainties and a notation of how thatuncertainty was determined (in this case from the standard deviation of several measurements).
  2. The accepted value is listed for comparison to measured values
  3. The percent error in each measurement is reported as a preparation for the discussion.

Discussion.

Both measurements agree within experimental error with the accepted value. Obviously, Procedure #1 is more precise, but its precision could have been improved by the use of a micrometer rather than the vernier caliper as the uncertainty in the length measurements dominate the uncertainty of the final result. The measurements of the mass (69.37+-.02 g) have an uncertainty of 0.03%. The length measurements using the caliper (2.75+-.01 cm) have anuncertainty of 0.36%. A micrometer is accurate to 0.001 cm. This is an improvement of an order of magnitude over the calipers which are accurate to 0.01 cm. Use of the micrometer would make the uncertainty in the length measurements comparable to the uncertainty in the mass.

Other factors which could affect the measurements of the volume are the temperature and the barometric pressure in the room. Either would change the dimensions of the copper cylinder. V (from temperature change of 5 C) = 0.002 cm^3, giving a percent change V/V = 0.03%. V (from pressure change of 10 mm Hg) = 7.5x10^-8, giving a percent change V/V = ~10^-6The temperature of the copper was not likely to change by 5 C during the measurement, but if it did, the vernier caliper could not measure that difference. The micrometer could. The volume change due to a pressure change is undetectable.

  1. The discussion is quantitative and a meaningful extension of the experiment.
  2. The discussion shows an understanding of the basic phases of this experiment as well as anunderstanding of the other parts of physics which relate to this experiment.

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