1 / 15

Experimental Error

Experimental Error. What is Experimental Error?. Aspects of the design of the experiment that cause results to be off. Every experiment has some sources of experimental error Anticipating sources or error beforehand can result in a better design of experiment.

juann
Download Presentation

Experimental Error

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Experimental Error

  2. What is Experimental Error? • Aspects of the design of the experiment that cause results to be off. • Every experiment has some sources of experimental error • Anticipating sources or error beforehand can result in a better design of experiment

  3. Things that are NOT Exper. Error:Blunders or Mistakes • These are goofs or accidents that happen during the lab • “We measured wrong” • “We calculated wrong” • “We spilled some of our test sample” • “We forgot to press tare”

  4. Examples of Experimental Error:Uncertainty in Measurements • All measurements have a guessed last digit • Therefore there is inherent error in all measurements and calculations with these measurements • Since this is constant, do not mention as a source of error in reports

  5. Examples of Experimental Error:Human Error • Ex: Using a stopwatch • Ex: Noting the temperature at which an object is completely melted

  6. Examples of Experimental Error:Difficulty in Measurement • Not the same as “We measured wrong” • This is caused by a legitimate reason that makes reading the instrument correctly difficult • Examples: • Measuring height of counter • Measuring diameter of balloon

  7. Examples of Experimental Error:False Assumptions • Not incorrect assumptions, but assumptions that aren’t 100% true • Examples • Using odometer to measure distance from house to school • Using formula for sphere to calculate volume of a balloon • Assuming temp of metal is the same as the temp of the water it is in

  8. Examples of Experimental Error:“Varying Unvariables” • In a valid experiment, only independent variable should change. All other conditions should remain constant throughout experiment. • Sometimes other conditions vary that we did not foresee or that we have no control over • Examples • During an experiment, room temperature may fluctuate • Different amounts of light may reach each plant if near window or shadows • Air pressure in room fluctuates while measuring balloon volume.

  9. Examples of Experimental Error:Contamination of Chemicals • This one is a border-line blunder • May come from unclean glassware • Chemicals get old and change • Other people may have contaminated stock chemicals

  10. Your Turn: The volume of a rock is measured by water displacement. • Some water is placed in a cylinder and recorded. • A rock is placed in the cylinder and that volume is measured. • The 2 measurements are subtracted to obtain the volume of the rock.

  11. Your Turn: The volume of a rock is measured by water displacement.

  12. Your turn: The volume of a penny is determined by the following method. • Use a ruler to measure the diameter of a penny. • Calculate the radius of the penny. • Measure the height of the penny • Use the formula for a cylinder, v=πr2h.

  13. Your turn: The volume of a penny is determined by cylinder formula.

  14. In Gas Laws Lab, Station #9 • Did your results support Charles’ Law? • What were some sources of error?

  15. Pick up your lab notebooks from table # 3 in the back of the room. • Grades posted include everything except extra credit CLC points.

More Related