Calculating Error Bars In Physics
Contents |
and Graphs Sidebar PHY124 Navigation Home Instructions Sections Uncertainty, Error and Graphs Lab 1 - The Oscilloscope Lab 2 - The Electric Field Lab 3 - DC Circuits Lab 4 - Magnetic Force 1 calculating error bars for graphs Lab5/6 Magnetic Field/Induction Lab5/6 Charge-to-Mass Ratio (e/m) of the Electron Lab calculating error bars for percentages 7 AC Circuits Lab 8 Optics: Reflection, Refraction and Images Lab 9 Interference and Diffraction Lab 10 Atomic calculating error bars from standard deviation Spectra Plotting Tool Blackboard phy124:error_and_uncertainty Table of Contents Uncertainty, Error and Graphs Uncertainty in measurements An inspirational message from 1600 for care in experimentation Notation Error Absolute Error Relative
Calculating Error Bars In Excel
Error Random Error Systematic Error Propagation of Errors Obtaining Values from Graphs An experiment with the simple pendulum: Things one would measure Estimate of error in the length of the string Error in the period Making a plot of our data Uncertainty, Error and Graphs Uncertainty in measurements In physics, as in every other experimental science, one cannot how to calculate error bars by hand make any measurement without having some degree of uncertainty. A proper experiment must report for each measured quantity both a “best” value and an uncertainty. Thus it is necessary to learn the techniques for estimating them. Although there are powerful formal tools for this, simple methods will suffice in this course. To a large extent, we emphasize a “common sense” approach based on asking ourselves just how much any measured quantity in our experiments could be “off”. One could say that we occasionally use the concept of “best” value and its “uncertainty” in everyday speech, perhaps without even knowing it. Suppose a friend with a car at Stony Brook needs to pick up someone at JFK airport and doesn't know how far away it is or how long it will take to get there. You might have made this drive yourself (the “experiment”) and “measured” the distance and time, so you might respond, “Oh, it's 50 miles give or take a few, and it will take you one and a half hour
Error Bars Kaori Miyajima SubscribeSubscribedUnsubscribe11 Loading... Loading... Working... Add to Want to watch this again later? Sign in to add this video to a playlist. Sign in Share More Report Need to report the video? how to calculate error bars for qpcr Sign in to report inappropriate content. Sign in Transcript Statistics 1,482 views 8
How To Calculate Error Bars In Excel 2010
Like this video? Sign in to make your opinion count. Sign in 9 1 Don't like this video? Sign in
How To Calculate Uncertainties In Physics
to make your opinion count. Sign in 2 Loading... Loading... Transcript The interactive transcript could not be loaded. Loading... Loading... Rating is available when the video has been rented. This feature is http://skipper.physics.sunysb.edu/~physlab/doku.php?id=phy124:error_and_uncertainty not available right now. Please try again later. Published on Dec 16, 2013Error bars! Category People & Blogs License Standard YouTube License Show more Show less Loading... Autoplay When autoplay is enabled, a suggested video will automatically play next. Up next 02 HL00.B1.2 Plotting Data & Error Bars - Duration: 5:26. Dr. Dan Hogan 2,543 views 5:26 Errors, Percentage Uncertainties and Compound Errors - https://www.youtube.com/watch?v=ipvWcnCRx4E A Level Physics Revision - Duration: 4:33. GorillaPhysics 3,782 views 4:33 3 Ways To Cheat On Any Test!!! - Duration: 4:57. Nextraker 6,932,903 views 4:57 Excel Graphs With Error Bars Tutorial By Nestor Matthews - Duration: 14:12. Nestor Matthews 12,819 views 14:12 How to score A in CIE Alevel Physics 9702 - Duration: 13:05. TheMathsCentreCom 3,175 views 13:05 CIE Nov 2014 Paper 5 9701/51 - Duration: 53:31. Allery Chemistry 997 views 53:31 Error and Percent Error - Duration: 7:15. Tyler DeWitt 114,233 views 7:15 1-3 Uncertainty & Measurements - Duration: 3:01. Truckee AP Physics 1 3,599 views 3:01 Making a Graph in Plotly with Error Bars - Duration: 6:22. Rhett Allain 926 views 6:22 Excel: Graphing with separate Error Bars of Standard Deviation - Duration: 6:38. Peter Stanley 13,031 views 6:38 Simple Calculations of Average and the Uncertainty in the Average - Duration: 4:22. MisterTyndallPhysics 30,635 views 4:22 CSEC Physics: Gradient and Intercept of a Graph(Plotting of an Actual Graph) - Duration: 9:55. Sciencetutr 5,267 views 9:55 How to add error bars to Excel graphs - Duration: 8:16. QuantumBoffin 104,151 views 8:16 A Level Physics ISA Help Part 4 - Combining Uncertaint
dividing Is one result consistent with another? What if there are several measurements of the same quantity? How can one estimate the uncertainty of a slope on a graph? Uncertainty in a single measurement Bob weighs himself on his bathroom scale. The smallest divisions on the scale are 1-pound marks, so the http://spiff.rit.edu/classes/phys273/uncert/uncert.html least count of the instrument is 1 pound. Bob reads his weight as closest to the 142-pound mark. He knows his weight must be larger than 141.5 pounds (or else it would be closer to the 141-pound mark), but smaller than 142.5 pounds (or else it would be closer to the 143-pound mark). So Bob's weight must be weight = 142 +/- 0.5 pounds In general, the uncertainty in a single measurement from a single instrument is half the error bars least count of the instrument. Fractional and percentage uncertainty What is the fractional uncertainty in Bob's weight? uncertainty in weight fractional uncertainty = ------------------------ value for weight 0.5 pounds = ------------- = 0.0035 142 pounds What is the uncertainty in Bob's weight, expressed as a percentage of his weight? uncertainty in weight percentage uncertainty = ----------------------- * 100% value for weight 0.5 pounds = ------------ * 100% = 0.35% 142 pounds Combining uncertainties in several quantities: adding or subtracting When calculating error bars one adds or subtracts several measurements together, one simply adds together the uncertainties to find the uncertainty in the sum. Dick and Jane are acrobats. Dick is 186 +/- 2 cm tall, and Jane is 147 +/- 3 cm tall. If Jane stands on top of Dick's head, how far is her head above the ground? combined height = 186 cm + 147 cm = 333 cm uncertainty in combined height = 2 cm + 3 cm = 5 cm combined height = 333 cm +/- 5 cm Now, if all the quantities have roughly the same magnitude and uncertainty -- as in the example above -- the result makes perfect sense. But if one tries to add together very different quantities, one ends up with a funny-looking uncertainty. For example, suppose that Dick balances on his head a flea (ick!) instead of Jane. Using a pair of calipers, Dick measures the flea to have a height of 0.020 cm +/- 0.003 cm. If we follow the rules, we find combined height = 186 cm + 0.020 cm = 186.020 cm uncertainty in combined height = 2 cm + 0.003 cm = 2.003 cm ??? combined height = 186.020 cm +/- 2.003 cm ??? But wait a minute! This doesn't make any sense! If we can't tell exactly where the top of Dick's head is to within a couple of cm, what difference does it mak