Lab Final Flashcards
What is an uncertainty?
An uncertainty is a phenomena that cuases your results to deviate from the true value
What is the true value and is it known?
A true value is the actual value of any measurement, in physics the true value is never know so we use uncertainty analysis
What is uncertainty analysis?
Uncertainty analysis is a technique that shows how confident we are in opur results based on the method and instrument being used.
Uncertainty analysis is also called?
Error Analysis
Name the 2 misconceptions concerning experimental uncertainties?
1) mistakes are not uncertainties (they are supposed to be fixed), are called blunders 2) the fact that people think that uncertainty = experimental - true value –> just remeber that we do not know the true value. even though we use known values they are somewhat of a reference rather than the actual value.
Name 2 deviations from the true value? Define them? How would they look like in a bullseye map?
Accuracy and Precision, accuracy is how close you are to the true value while precision is how well the results have been determined (grouping and relaibility). High precision the values are listed close to each other, the closer these dots are the more precise they are. High accuracy the values are closer to the true values (bullseye), the closer they are to the bulleye the more accurate they are.
What are the true values?
The true values in physics are a predicted value that are assumed to be right. However, true values are never known in physics, they are used for uncertainties so we can get an idea as to how significant the results are.
List the categories of uncertainties?
Random Uncertainties Systematic Uncertainties Blunders
Give a definition of the categories of uncertainties and any sub level categories that are included within them?
Random Uncertainties: when you take repeated measurements that have an equal chance of being higher or lower than the true value. The sources of random uncertainties cause random fluctuations in the results.
SOURCES:
instrumental: limitations due to the resolution of instrument
observational: is due to the judgements of the observer (non-biased)
environmental: unpredictable changes to the environment that cause fluctuations.
Systematic Uncertainties: repeated measurements that are more likely to be higher or lower than the true value. The sources of systematic uncertainties cause the average readings to be consistently too high or too low.
SOURCES:
instrumental: poor calibration
observational: constant bias in the observation
environmental: the area surrounding affects the results consistently
theoretical: when you miscalculate theoretical values (ex. you forget to account for air resistance for an object free falling)
Blunders: refer to mistakes made during the experiment. (SHOULD BE CORRECTED AND ARE NOT A VALID UNCERTAINTY)
What is the difference between the different categories of uncertainties?
The difference between these different types of uncertainties lies in how they affect the quality of the results.
What deviation from the true vale do random uncertainties affect?
Random Uncertainties affect the precision of the measurement.
What is parallax?
Parallax has to do with the angle you measure something with. To avoid any parallax line up your field of view parallel to eye level.
What deviation from the true vale do systematic uncertainties affect?
Systematic Uncertainties affect the accuracy of the measurement.
Can systematic uncertainties be corrected?
Yes, sys. uncertainties can be corrected after an experiment if the values are consistently high or low.
What is the difference between random and systematic uncertainites?
The difference lies in how they affect the results: Randomly (random uncertainties) or biased (consistently, systematic uncertainties) towards a high or low value.
However, a blinder would be due to the cause of the uncertainty –> like misusing equipment.
