Uncertainty Flashcards

1
Q

Give 3 different ways we can reduce uncertainty.

A
  • Increase resolution of instrument/ ie. use instrument with smaller intervals.
  • Take repeated readings
  • Size of measurement taken.
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2
Q

How do we work out the uncertainty of equipment where one judgement is made?

A
  • ±1/2 of smallest interval
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3
Q

How do we work out the uncertainty of equipment where two judgements are made (ie. 2 sources of uncertainty)?

A
  • ±1/2 of smallest interval + - ±1/2 of smallest interval
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4
Q

Reading: 1660mg, without any info on resolution of equipment, what would the uncertainty be?

A

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.

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5
Q

Reading: 1663mg, without any info on resolution of equipment, what would the uncertainty be?

A

-±1
- Look at what place value the last significant digit is, in this case its in the ones.

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6
Q

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.

A
  • 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.
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7
Q

How can uncertainty be calculated when we have repeated measurements?

A
  • Calculate mean of repeated measurments.
  • Range/ 2 = uncertainty of the repeated measurements.
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8
Q

How do we calculate percentage uncertainty in repeated measurements?

A

uncertainty/ mean value x 100.

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