paper 3A practical skills Flashcards
how is the minumun nomber of data points you need
5
if a straight line graph is produced what do you need to state
if it passes through the origin or not
need to state the range and inteveal of you _______ _______
indipendent veriable
depndent veriable
the thing you measuring
independent veriable
the thing you changing
you need to state how you will _____ the _______
reduce, uncertency
concordent
in agreement
allways state that you should repeat this measurment untill results are…
concordent and then take the avarge
systimatic erorrs reduce…
ramdom erorrs reduce…
accurecy
accurecy and precision
what can you do to reduce percentage uncertency when you have a fixed absalute uncertency
what can you do to reduce absalute uncertency
use larger values in the exproment as the absalute uncertency will then be a smaller percentage of the value
use equipment or measuring technecs that have greater resolution
what can you do to reduce random errors
- carry out repeats untill concordent results are achieved
- remove anomalies
- calculate mean / avarge
how can you detect systematic errors
measure a known value
(you do this when calibrating equipment)
when questions ask you to calculat the uncertency which one are they refering to?
absalut uncertencey
(only calculate % uncertency if the question specificaly askes for it)
what is the diffrence between a reading and a measurment
what is the absalute uncertency of a reading and of a measurement
a reading is were you only make 1 judgment (e.g taking the reading from a balence)
a measurement is when you make 2 judgments (e.g mesuring a distence with a ruler)
reading is 1/2 x reselution
measurement is 1 x reselution
(as measurement is 1/2 x reselution + 1/2 x reselution)
if the experomenter creates more uncertency by carrying out the experoment then the qequipment then what do you do (e.g if reaction time is less then the reselution of a stopwatch)
take the largest uncertency wich would be from the experomenter (e.g the reaction time)
what is the uncertency of values given (e.g nomber of lines per meater = 3.5x10^3)
absalute uncertency is +- the last sig fig (e.g 0.1x10^3)
how to calculate the absalute uncertency for the mean of repeted values
e.g 5 6 7 8 9 25
find the absalute uncertency:
remove anomilys results
then
range/2
9-5=4
4/2=2
∴5+6+7+8+9 /5 =7
∴answer is 7+-2
when:
adding or subtracting data you ____ absalute uncertainties
multiplying or deviding data you _____ percentage uncertenties
rasing data to a power you ______ percentage uncertenties
add
add
multiply
how to you find graidinets from straight line graphs
how do you find graidient form curved graphs
draw the largest possible gradient triangle (have to draw the tiangle)
draw a tangent at the point that is wanted and find the gradient of that tangent
error bars a graphical representation of…
error bars should be…
when is a reult anomylis
on a graph how do find the absalute uncertency in gradient
absalute uncertency
drawn on all experomental values you take
when teh line of best fit does not pass through any of the values error bars
best line of best fit - worst line of best fit
are zero errors
what error is this
when the quipment fails to read 0 when it should do
systematic
for point on a graph you must use…
x
do you have to stater form 0 on a graph
no you are suposed to only use the part of the graph that is relevent to the data e.g start on the y and x axis a 3
if they ask how you can reduce uncertency always think about:
- repeat untill values concordent then take avarge ∴ reducing random errors
- technology (camras, light gates, motion sensers linked to data loger) ∴ reduce human error
- reduce paralax error
- repeat, find anomalies, discard anomalies
