Errors & Uncertainties

Question 1

Uncertainty

Answer 1

Variation in a measurement because of inprecision in the device

Question 2

absolute uncertainty

Answer 2

The magnitude of the uncertainty associated with a measurement or value

Question 2

relative uncertainty

Answer 2

absolute uncertainty/measurement x 100

Question 2

Abs Uncertainty in digital vs analogue

Answer 2

Digital +- smallest incriment (unit)
Analogue +- half of smallest incriment

Question 3

random error

Answer 3

Error that occurs due to equipment limitation and deviates measurmeents from their trend (eg. human error)

Question 4

systematic error

Answer 4

A type of error that causes readings to differ from the true value by a consistent amount each time a measurement is made.

Question 5

parallax error

Answer 5

error that occurs due to the incorrect positioning of the eye

Question 6

zero error

zero error

Answer 6

Indidcation that a measuirng device gives false reading when the true value of the substance measured is zero

Question 7

Uncertainties when added

Answer 7

can all be added to give total uncertainty

Question 8

Uncertainties when multiplied

Answer 8

express as percentage of values, add all together, then take total percentage uncertainty form final value

Question 9

fractional uncertainty

Answer 9

absolute uncertainty/ data value (for rate constant)

Question 10

Sig figs rules

Answer 10

• leading zeros are UNsignificant
• zeros between numbers ARE significant

Question 11

Sketched graph vs drawn graph

Answer 11

Sketched = labelled axis
Drawn = labelled axis, scaled axis, plotted points

Question 12

significant figure rule for division

Answer 12

report answer to lowest sig fig in equation

Question 13

significant figure rule when adding

Answer 13

whatever the sums sig figs is

Question 14

uncertainty for difference in measurement

eg temp

Answer 14

add absolute uncertainties

Question 15

7 basic SI units

Answer 15

1. meters
2. kilograms
3. seconds
4. ampere
5. kelvin
6. mole
7. candela