Uncertainty Flashcards
Give 3 different ways we can reduce uncertainty.
- Increase resolution of instrument/ ie. use instrument with smaller intervals.
- Take repeated readings
- Size of measurement taken.
How do we work out the uncertainty of equipment where one judgement is made?
- ±1/2 of smallest interval
How do we work out the uncertainty of equipment where two judgements are made (ie. 2 sources of uncertainty)?
- ±1/2 of smallest interval + - ±1/2 of smallest interval
Reading: 1660mg, without any info on resolution of equipment, what would the uncertainty be?
Reading: 1660mg, without any info on resolution of equipment, what would the uncertainty be? - ±10
- Look at what place value the last significant digit is, in this case, its the tens.
Reading: 1663mg, without any info on resolution of equipment, what would the uncertainty be?
-±1
- Look at what place value the last significant digit is, in this case its in the ones.
If we have 10 leaves that need to be measured, what would lead to lowest uncertainty
1.) Measuring all the leaves together (gives length of 2.1mm)
2.) Measuring one leaf at a time and WHY?
Assume, that the uncertainty for measuring 1 leaf is ±0.cm.
- Measure length all leaves stacked on top of each other.
- 10 leaves together: 2.1 ±0.1
- 1 leaf: 0.21 ±0.01(reduces the uncertainty.)
- We can do this because percentage uncertainty in measuring 1 leaf = same as 10 leaves.
How can uncertainty be calculated when we have repeated measurements?
- Calculate mean of repeated measurments.
- Range/ 2 = uncertainty of the repeated measurements.
How do we calculate percentage uncertainty in repeated measurements?
uncertainty/ mean value x 100.