Practicle Skills Flashcards
What is an independentvariable?
A variable which is changed by the experimenter
What is a dependant variable?
A variable which is measured by the experimenter
What is a controll variable?
A variable which is kept constant
What is meant by a systematic error
An error which affects all results in the same way.
How can systematic errors be reduced?
Ensure equipment is calibrated correctly
What is meant by a random error?
An error which affects all results in an unpredictable way.
How can random errors be reduced?
Take repeat readings
What is the absolute uncertainty in a measurement made with a meter ruler?
Plus/minus 1mm
How is percentage uncertainty calculated?
Absolute uncertainly / measurement x 100
What 2 general strategies should be used to reduce percentage uncertainty?
- Reduce the absolute un certainty, eg. By using a measuring device with higher resolution
- Increase the measurement size eg by using a longer length of wire.
When quantities are added what happens to their absolute uncertainty?
They add
When quantities are subtracted what happens to their absolute uncertainty?
They add
When quantities are multiplied/divided, what happens to their percentage uncertainties?
They add.
When a quantity is raised to a power, what happens to its percentage uncertainly?
It multiples by the power
When a quantity is multiplied by n, what happens to the absolute uncertainty?
It multiplies by n
When a quantity is divided by n, what happens to the absolute uncertainty?
It divides by n
When a quantity is multiplied/divided by n, what happens to the percentage uncertainly?
Nothing
How do you calculate the percentage uncertainty in a range of data?
Plus/minsus half the range/ mean x100
How do you calculate the percentage uncertainty in the gradient of a line of best fit?
Plus or minus 1/2 x(difference between steepest and shallowest gradient) / best fit gradient X 100
How do you calculate the percentage uncertainty in the y-intercept of a line of best fit.
+- 1/2 X(difference between steepest and shallowest y intercept ) / best fit line y intercept X100
How do you calculate percentage difference
In an experimental result from the theoretical result?
Difference between results / theoretical results X100
