Measurements and Errors Flashcards
(15 cards)
How do you convert from Joules to Electron-Volts (eV)?
Multiply Joules by 1 volt and 1.16x10^-19 (magnitude of charge of an electron).
Energy = Charge x Voltage
How do you convert from Joules to Kilo Watt Hour (kWh)?
Multiply Joules by 1000 and by 3600.
Energy = Power x Time
What is the difference between Systematic errors and Random errors?
Random error is unpredictable variation leading to a spread of values, while Systematic error differs a fixed amount from the true value.
How can Random errors be reduced?
By repeating the measurements and calculating the mean.
How can Systematic errors be reduced?
By changing the instrument used or the method.
Which type of error is more important to reduce?
Systematic errors, as they affect all readings due to issues with the method or instrument.
How do you calculate the Percentage Uncertainty of a single reading?
Divide the absolute uncertainty by the original reading and multiply by 100.
How do you calculate the Percentage Uncertainty of repeated readings?
Divide half the range (absolute uncertainty) by the mean and multiply by 100.
What is the definition of Resolution?
The smallest change an instrument can record that causes a visible change to the reading.
How do you Add/Subtract uncertainties?
You add the absolute uncertainties.
Why may individual points on a graph not have associated error bars?
Each data point may have its own uncertainty, leading to varying error bars.
What is the difference between Readings and Measurements?
Readings are a single value found, while Measurements are the difference between two readings.
What is the uncertainty of a Reading?
+- half the smallest division.
What is the uncertainty of a Measurement?
+- the smallest division.
What are Orders of Magnitude in Estimation?
Powers of ten describing the size of an object.
E.g. the diameter of nuclei is around 10^-14 m.
