practical skills Flashcards
why should you keep variables constant
so the experiment being carried out is a fair test
what is a control variable
variables kept constant in a experiment
what is a independent variable
the thing you change in an experiment
dependent variable
the thing you measure in an experiment
what is true about every numerical measurement
they have an experimental uncertainty
what is the smallest uncertainty you can have
half one division on the measuring instrument used
with a thermometer where one division is 2 degrees what will a measurement of 30 degrees be measured to
30 ± 1
what does the ± sign mean
range which the true value lies in
what is the uncertainty when measuring with a ruler
double the smallest uncertainty
why do you have to double the uncertainty when using a ruler
because you measure at each end of the object so there’s uncertainty at each end
what are two types of error
random error and systematic error
what does random error do to readings
cause readings to be spread about the true value
what do what does systematic error do to readings
cause each reading to be different by the same amount which affects the accuracy of your results
how can you reduce uncertainty
*repeat each measurement
*take mean of repeated measurements
*bigger uncertainty means bigger range
*eliminate anomalous results
* use equipment with smaller intervals
*use computers and data loggers
*calibrate equipment
how to work out fractional uncertainty
divide uncertainty by measurement
how do you work out percentage uncertainty
divide uncertainty by measurement and multiply by 100
when adding or subtracting data what do you do to uncertainties
add absolute uncertainty
when multiplying or diving data what do you do to the uncertainties
add absolute uncertainties
when raising data to the power what do you do to the uncertainty
times uncertainty by power
what do error bars show
uncertainty of individual point
how do u calculate the uncertainty using graphs
the different between the best and worst graph
what is true about uncertainty and signifiant figures
you always have to round your data your uncertainty to the same number of sf as the data with the least number of sf
when drawing graphs where should the dependent and independent variable go
dependent on the y axis
and independent on the x axis
what are words you should use to show what the data shows
*precision
*repeatable
*reproducible
*valid
*Accurate
what does precision mean
precision is the amount of reliability the smaller the amount your data spreads from the mean the more precise it is and depends on the amount of random error
what does repeatable mean in terms of data
you can repeat an experiment and get the same result
what does reproducible mean in terms of data
someone else can recreate your experiment using different equipment or methods
what does valid mean in terms of data
original question is answered using the precise data
what does accurate mean in terms of data
result is really close to the true answer
