Module 1 and 2 Flashcards
Absolute Uncertainties:
The interval that a value is said to lie within, with a given
level of confidence.
Accuracy
A measure of how close a measurement is to the true value.
Analogue Apparatus
Measuring apparatus such as rulers, beakers and
thermometers that rely on the experimenter reading off a scale to determine the
measurement
Anomalies
Data points that don’t fit the pattern of the data. You should determine
why an anomalous result has occurred before removing it. Repeat readings help
remove anomalies
Control Variables
Variables that must remain the same throughout an
experiment so as to not affect the results
Dependent Variables
The variable being measured in an experiment. It is
dependent on the independent variable. The dependent variable should be plotted
on the y-axis of a graph.
Digital Apparatus
Measuring apparatus such as ammeters, voltmeters and digital calipers that digitally measure and display a measurement.
Fiducial Marker
A thin marker, such as a splint, that is used to ensure readings
are taken from the same place each time. They are used to improve the accuracy
of measurements
Gradient
The change in the y-axis value over the change in the x-axis value
between two points. If the graph is curved, a tangent can be drawn to calculate the
gradient at a specific point.
Independent Variables
The variable that is changed by the experimenter in an
experiment. The independent variable should be plotted on the x-axis of a graph.
Line of Best Fit
A line drawn on a graph to demonstrate the pattern in the plotted
data points.
Percentage Uncertainties
The uncertainty of a measurement, expressed as a percentage of the recorded value
Precision
A measure of how close a measurement is to the mean value. It only
gives an indication of the magnitude of random errors, not how close data is to the
true value.
Prefixes
Added to the front of units to represent a power of ten change
Random Errors
Unpredictable variation between measurements that leads to a
spread of values about the true value. Random error can be reduced by taking
repeat measurements
Repeatable
The same experimenter can repeat a measurement using the same
method and equipment and obtain the same value
Reproducible
An experiment can be repeated by a different experimenter using
a different method and different apparatus, and still obtain the same results
Resolution
The smallest change in a quantity that causes a visible change in the
reading that a measuring instrument records.
Resolution of Forces
The splitting of a force into its horizontal and vertical
components
Scalar Quantities
A quantity that only has a magnitude, without an associated
direction. Examples include speed, distance and temperature.
SI Units
The standard units used in equations. They are: meters, kilograms,
seconds, amps, Kelvin and moles
Significant Figures
A measure of a measurement’s resolution. All numbers
except zero are counted as a significant figure. When zeros are found immediately
after a decimal place, they too are counted.
Systematic Errors
Causes all readings to differ from the true value by a fixed
amount. Systematic error cannot be corrected by repeat readings, instead a
different technique or apparatus should be used.
Triangle of Forces
A method of finding the resultant force of two forces. The two
forces are joined tip to tail and the result is then the vector that completes the
triangle.
Vector Quantities
A quantity that has both a magnitude and an associated
direction. Examples include velocity, displacement and acceleration
Vernier Scales
The type of scale used on calipers and micrometers, that involve
reading from a fixed scale and a moving scale to produce accurate
measurements
Zero Errors
A form of systematic error, caused when a measuring instrument
doesn’t read zero at a value of zero. This results in all measurements being offset by a fixed amount
To plan an experiment you need (9 steps)
- Identify the apparatus required e.g. for measuring instantaneous velocity of a car down a
ramp you’ll need light gates, a car, ramp and a data logger. - Know the range (maximum and minimum readings possible) and resolution (the smallest
change in the input that gives a change in reading) of all measuring instruments e.g. 0.1mm
for Vernier calipers and 0.01mm for micrometer screw gauges. - Calibrate instruments e.g. setting a mass balance to 0 when it is empty to avoid systematic
error. - Measure the variables using appropriate instruments and techniques, e.g. temperature
should be measured with a thermometer at eye level. - Identify control variables and keep them constant, e.g. when using Charles’ law to
determine absolute zero, pressure must be constant. - Know whether to take repeats, usually 3 repeats is sensible but if the results are very
inconsistent (low precision) then more are necessary. - Identify, discuss or resolve health and safety issues e.g. reduce exposure times when using
radioactive sources. - State a hypothesis, this is a prediction of what will happen and why, the hypothesis is tested
during the experiment and the results are said to either support or contradict the
hypothesis. - Apply the data to the situation to determine a conclusion and whether the data supports the
hypothesis, identify sources of uncertainty and talk about how they could have been
reduced.
Exa (E)
10^18
peta (P)
10^15
Tera (T)
10^12
Giga (G)
10^9
Mega (M)
10^6
Kilo (k)
10^3
hecto (h)
10^2
centi (c)
10^-2
milli (m)
10^-3
micro (µ)
10^06
nano (n)
10^-9
pico (p)
10^-12
femto (f)
10^-15
atto (a)
10^-18
Discrete
only certain values can be taken, e.g. number of objects. Display on scatter graphs and
bar charts
Continuous
can take any value on a scale e.g. current in a circuit. Display on line or scatter
graph
Categoric
values that can be sorted into categories e.g. types of material. Display on a pie or bar
chart
Ordered
data that can be put in ordered categories e.g. low, medium, high. Display on bar chart
ln(AB)
ln(A) + ln(B)
