Uncertainties Flashcards
What are the 3 different types of uncertainties?
Systematic Uncertainties
Random Uncertainties
Scale reading uncertainties
How do systematic uncertainties affect the readings?
Systematic uncertainties affect all readings in the samemanner, making them too small or too large.
How are systematic uncertainties caused?
Often caused by
•poor experimental technique (for example reading the wrong scale).
- taking innacurate measurments.
- badly callibrated equipment (e.g. a balance that has not been ‘zeroed’ properly).
How are systematic uncertainties often shown?
Straight line graphs that don’t go through the origin
What are scale reading uncertainties?
No matter how precise a scale is, there is always a limit to how accurately a measurement can be taken.
What is the uncertainty in a digital scale?
± 1 of least significant digit
What is the uncertainty of analogue scale?
± ½ of smallest scale division
What are random uncertainties?
Whenever we repeat an experiment, there will always be some random variation in the results, despite our best efforts to control all variables.
Name some examples of random uncertainties.
Examples include human reaction times which can vary from reading to reading.
How do you calculate the random uncertainties
Random uncertainty = max. value ‐ min value
number of values
What does taking more measurements reduce what type of Uncertainty
Random
What is an absolute uncertainty?
the actual size of the measured uncertainty. These take the form measurement ± uncertainty, e.g. (0.52 ± 0.01)V
What is a percentage uncertainty?
the size of the uncertainty as a percentage of the measurement. This can be writen instead as 0.52V ± 1.9% (0.01 is 1.9% of 0.52)
How do you calculate a percentage uncertainty?
Uncertainty of X / X x100
What do percentage uncertainties allow?
comparisons between different uncertainties
The uncertainty in what value should be take as the largest uncertainty of the quantities used to calculate it
calculate
What is the definition for accurate
A measurement is accurate if the mean value is equal or close to the true value.
What is the definition for precise
A measurement is more precise if it is given to a larger number of significant figures.
What is the definition for reliable
Measurements are said to be reliable if they all give the same or similar values when repeated.
What does tera (T) mean?
x10^12
What does giga (G) mean?
x10^9
What does mega (M) mean?
x10^6
What does kilo (k) mean?
x10^3
What does centri (c) mean?
x10^-2
What does milli (m) mean?
x10^-3
What does micro (μ) mean?
x10^-6
What does nano (n) mean?
x10^-9
What does pico (p) mean?
x10^-12
