1 - Working as a Physicist Flashcards
How many base units are there?
7
what are the si base units?
- mass, kilogram, kg
- length, metre, m
- time, second, s
- current, ampere, A
- temperature, kelvin, k
- amount of substance, mole, mol
Derive the base units for:
1 - newtons (N)
2 - joule (J)
3 - pascal (Pa)
1 - kg m s–2
2 - kg m2 s–2
3 - kg m–1 s–2
what is the resolution of measuring instruments?
what each decision on a scale represents
what’s the benefit of digital instruments as opposed to analogue instruments?
-Have greater accuracy and resolution
-show measure values as digits
-easy to use
what’s the resolution of a micrometer?
0.01mm
what’s the resolution of vernier callipers?
0.1mm
What are the benefits of a data logger?
-readings are taken with higher degrees of accuracy
- reduction in human error
-readings can be taken over a long period of time
-readings can be taken in a very short time
-reduction in safety risks
what is error?
the difference between the true value and the measured result
what is random error?
unpredictable fluctuations in an instruments readings as a result of uncontrollable factors
this effects the precision of the measurements take
how can you reduce random error?
Take repeat measurements and calculate an average
what is systematic error?
arise from faulty instruments or from flaws in the experimental method
it affects the accuracy of the readings
how can you reduce systematic error?
instruments should be recalibrated or different instruments should be used
corrections or adjustments should be made to the technique
what is zero error?
a type of systematic error that occurs when an instrument gives a reading when i fact the true reading is zero
introduces a fixed error into the readings which must be accounted for when results are recorded
what is precision?
this describes the spread of results and is only influenced by random effects
what is accuracy?
describes how close a measurement is to the true value and is influenced by random and systematic errors
what is uncertainty?
an estimate of the difference of the true value and a measurement
the interval in which the true value can be considered to lie with a given level of confidence
how do you work out percentage uncertainty?
(uncertainty / measured value) * 100%
what is the uncertainty in:
1 - a reading
2 - a measurement
3 - repeating data
4 - digital readings
1-half the smallest division
2-one smallest division
3-half the range
4-the last significant digit
