prep for the ISA and General physics Flashcards
When recording results in a table, how many significant figures do you give it to?
Give it to the no. of significant levels of the instruments.
Give any means calculated to the same no. of significance levels.
If you process data which are given to different numbers of significant figures, how many do you use in the answer?
The no. of significant figures used in the value with the smallest amount.
How can random errors be reduced?
Taking repeat readings.
What is systematic error?
Errors that show a trend, bias or pattern. It deviates from the true reading by a fixed amount each time.
How is the uncertainty in a set of values found?
There are 3 options.
Random error. Uncertainty=(±range÷2) units.
Precision of instrument. Uncertainty=± smallest units on the scale.
Judgment. Like having kinks in a wire. Uncertainty=±(3 X precision of the instrument.)
Pick the largest.
Always have units.
If we have to combine the errors from different measurements and they have different units, what do we do?
Find % uncertainty.
(Uncertainty ÷ mean value.) X 100.
Never give to more than 2 sig figs.
How do you combine % uncertainties ?
They add up if you X, +, - or ÷
If a value is squared, multiply it by 2.
If a value is square rooted, divide by 2.
How would you find the percentage of something?
How would you find 1.3% of 9.42?
(9.42÷100) X 1.3
What is an accurate measurement?
An accurate measurement is one where independent measurements cluster about the true
value of the measured quantity.
What is a precise measurement?
A precise measurement is one where independent measurements of the same quantity
closely cluster about a single value that may or may not be the correct value.
Does systematic errors affect precision or accuracy?
Only the accuracy.
When drawing a table, what should each column heading have?
A quantity and a unit. The units should be give in brackets.
How big should the graph be?
Big enough so that the plotted points take up at least half the page.
When drawing a graph, when should the axis start ?
At the origin. Both should start at 0.
When drawing a graph, what divisions in the axis aren’t allowed?
3, 6, 7, 9 and others like that.
