measurements and there errors Flashcards
(28 cards)
what are SI units
the fundamental units
other then SI units how can units be derived
from there equations
what is centi
10-2
what is pico
10-12
what is femto
10-15
how do you convert mega electron volts into joules
1eV=1.6 x 10 -19 J
how do you convert kilowatt hours into joules
1kW=1000J/s 1 hours =3600s
1kWh=1000 x 3600
what do random errors effect
precision
how can you reduce random error
take at least 3 repeats
use computers
use appropriate equipment
what do systematic errors effect
accuracy
examples of systematic errors
zero error
parallax error
how can you reduces systematic error
-calibrate apparatus by measuring a know value
-in radiation experiments record background radiation
-read the meniscus at eye level
what does precise mean
measurements are consistent, they fluctuate slightly about a mean value- precise does not mean accurate
what does repeatability mean
if the original experimenter can redo the experiment with the same equipment and method and get the same results its repeatable
what does reproducibility mean
if the experiment is redone by a different person or with different techniques and equipment and same result is found it is reproducible
what does resolution mean
the smallest change in the quantity being measured that gives a recognisable change in reading
what does accuracy mean
a measurement clos to the true value is accurate
how can you reduce fractional or percentage uncertainty
measure larger quantities
what is a reading and what are the rules of uncertainties in them
readings are when one value is found and the uncertainty is equal to half the smallest division
what are measurements and what are the uncertainties in them
measurement are the difference between two readings and the uncertainty is the smallest division
what is the uncertainty for digital readings
its resolution
what is the uncertainty for repeated data
half the range
how you do combine uncertainties for adding or subtracting data
always add the absolute uncertainties
how do you combine uncertainties when multiplying or dividing
add the percentage uncertainties
