foundations of physics Flashcards
What are SI units?
Fundamental (base) units of physical quantities.
What is the SI unit of mass?
Kilogram - kg.
What physical quantity is measured in mol?
Amount of substance.
What is the SI unit of current?
Amperes (A).
Is the SI unit for temperature ℃ or K ?
K (kelvin) as this is the absolute scale.
What is the SI unit of length?
Metres - m.
What quantity is measured in seconds?
Time.
What multiplier is associated with the prefix kilo (k)?
1000 (10^3)
What multiplier is associated with the prefix femto (f)?
10^-15
What is accuracy?
● Accuracy is a measure of how close a
measured value is to the true, accepted value.
● If a experiment result is accurate it is very
close to the true value.
● In practice, the true value usually is not
known.
What is validity?
A measurement is valid if it measures what it is
supposed to be measuring. An experimental
procedure is valid if the obtained values provide
an answer to the question that is being asked.
What is a random error?
An error that occurs due to unexpected changes
during an experiment. These cannot be predicted
and they can cause repeated results to differ
from one another.
What is an anomaly?
An anomaly (also known as an outlier) is a data
point or a value in a set of results that does not fit
the trend of the data and is therefore an
unexpected result. These can happen as a result
of random errors during an experiment.
What is a systematic error?
An error that occurs due to faults in equipment or
experimental method. Systematic errors cause
the result to differ by the same amount each
time, making them predictable. They can occur
due to not calibrating an instrument correctly.
State three ways of reducing random
errors.
● Take at least three repeats and calculate a
mean (this increases the likelihood of identifying
anomalies).
● Use computers/data loggers.
● Use higher resolution equipment.
How can systematic error be reduced?
Calibrate apparatus before using e.g. zero the
balance when it is empty.
Is electronic noise in the circuit of an ammeter
random error or systematic error?
Random error, as it will cause fluctuations in
readings that affect precision and it cannot be
removed.
Why should you measure background radiation
before measuring the radioactivity of a source?
So that only the source’s radioactivity is
measured - by accounting for background
radiation, systematic error can be reduced.
What is precision?
How consistent/close together repeat readings
are - the closer they are, the more precise they
are.
What makes an experiment repeatable?
If the original experimenter can redo the
experiment with the same equipment and method
then get the same results, the experiment is
repeatable.
What makes an experiment reproducible?
What makes an experiment reproducible?
What is meant by resolution?
The smallest change in the quantity being
measured that gives a recognisable change in
reading
What is absolute uncertainty?
Uncertainty given as a fixed quantity.
How can percentage and fractional uncertainty be
reduced?
Measure larger quantities. For example, a longer
rope will have a smaller percentage uncertainty
than a shorter one.
What is the difference between a reading
and a measurement?
Readings are when one value is found,
measurements are when the difference between
two readings is found.
What is an order of magnitude?
Powers of ten which describe the size of an
object, and which can also be used to compare
the sizes of objects.
What is the order of magnitude for the
diameter of a nucleus?
10^-15 (femtometres)
What is meant by a scalar quantity?
A quantity that has only magnitude.
What is a vector quantity?
A quantity that has magnitude as well as
direction.
