Measurements and Errors Flashcards
Types of errors and uncertainties
What is the symbol and the magnitude of the prefix: tera
T
×10^12
What is the symbol and the magnitude of the prefix: giga
G
×10^9
What is the symbol and the magnitude of the prefix: mega
M
×10^6
What is the symbol and the magnitude of the prefix: kilo
k
×10^3
What is the symbol and the magnitude of the prefix: centi
c
×10^-2
What is the symbol and the magnitude of the prefix: milli
m
×10^-3
What is the symbol and the magnitude of the prefix: micro
μ
×10^-6
What is the symbol and the magnitude of the prefix: nano
n
×10^-9
What is the symbol and the magnitude of the prefix: pico
p
×10^-12
What is the symbol and the magnitude of the prefix: femto
f
×10^-15
SI unit for Amount of substance
Mole/mol
SI unit for Temperature
Kelvin/K
SI unit for Length
Metre/m
SI unit for Time
Second/s
SI unit for Mass
Kilogram/kg
SI unit for Current
Ampere/A
What is a Systematic Error?
An error that causes the measurements to differ from the true value by the same amount
What is a Random Error
An error caused by unpredictable circumstances and resulting in measurements that differ from the true value by varying amounts
Sources of Systematic Errors
- Imperfect Calibration
- Imperfect Methods of Observation
- Interference from the environment
Sources of Random Errors
- Mistakes made in inaccurate readings made by the experimenter
- Fluctuations in the reading on the instrument
How do you reduce Systematic Errors?
- Repeating the experiment using a comparable apparatus to identify the source of the error
- Accurate calibration of equipment
- Confirming experimental method against literature
How do you reduce Random Errors?
- Taking averages over multiple measurements, not including anomalous results
- Repeating the experiment and and averaging over all the measurements
Define Error
The difference between the measured value and the true value of measurement
Define Uncertainty
The degree to which we can say a measurement is accurate
Define Accuracy
A measurement is accurate if its value is close to the true/accepted value
Define Precision
A measurement is precise is its value is close to the average of measurements of the same quantity
Define Repeatability
A measurement is repeatable if the experiment can be repeated to obtain the same results under the same conditions
Define Reproducable
An experiment is reproducible if it can be reproduced by the same or an independent experimenter
How do you calculate percentage uncertainty?
Absolute uncertainty/value × 100
σ = ε/a × 100
