Practical Skills Flashcards
What is the main way to increase accuracy?
Take 3 repeat meanings and calculate mean
What reduces RANDOM error
More sensitive equipment to reduce uncertainty (eg smaller graduations)
What reduces SYSTEMATIC error
Calibrating equipment
How to work out uncertainty: analogue vs digital
Analogue: 1/2 smallest graduation
Digital: the resolution
When measurement gets smaller, does % uncertainty get bigger or smaller?
Bigger
% uncertainty formula
(Uncertainty/measurement) x 100
When you take 2 readings (eg length, temp) what is the % uncertainty formula?
(2 x uncertainty / quantity measured) x 100
Why is systematic error more problematic?
•affects all results
•dont realise
•affects mean
Light microscope’s vs electron microscope’s resolution
Light: 200nm
Electron: 0.1nm
Why do electron microscopes have a higher resolution?
Electrons have shorter wavelengths than light so there’s less diffraction (overlapping)
2 scales on the light microscope and where are they?
Stage micrometer (stage)
Eyepiece graticule (slide)
1 division on the stage micrometer=…
10 micrometres
