3.1 Measurements and their errors Flashcards
What is a newton in SI base units?
kg.m.s-2
What is a pascal in SI base units?
kg.m-1.s-2
What is a joule in SI base units?
kg.m2.s-2
What is a watt in SI base units?
kg.m2.s-3
What is a coulomb in SI base units?
s.A
What is a volt in SI base units?
kg.m2.s-3.A-1
What are all the prefixes in descending order?
Deca
Tera
Giga
Mega
Kilo
Milli
Micro
Nano
Pico
Femto
What is a random error?
An error in measurement caused by factors which vary from one measurement to another.
What is a systematic error?
An error having a non-zero mean, so that its effect is not reduced when observations are averaged.
What is a reading?
A value found from a single judgement.
What are some examples of equipment that take readings?
Thermometer
Top pan balance
Measuring cylinder
Digital meter
Geiger counter
Pressure gauge
What are some examples of equipment that take measurements?
Micrometer
Ruler
Vernier capiller
Protractor
Stowpwatch
Analogue meter
How do you calculate the absolute uncertainty for a reading?
Half the finest increment on the device.
How do you calculate the absolute uncertainty for a reading?
The finest increment on the device.
How do you calculate the percentage uncertainty?
(Absolute uncertainty)/ (reading) *100
How do you combine the uncertainty when adding 2 quantities together?
Add the absolute uncertainties
How do you combine the uncertainty when multiplying or dividing 2 quantities?
Add the percentage uncertainties
How do you combine the uncertainty when raising a quantity to the power n?
Multiply the percentage uncertainty by n
Which value in a calculation adds the most to the uncertainty of the answer?
The value with the largest percentage uncertainty.
What happens to the uncertainty when multiplying or dividing by a constant?
The absolute uncertainty is multiplied or divided too but, the percentage uncertainty remains the same.
What is precision?
The closeness of two or more measurements to each other
What is repeatable?
The original experimenter repeats the investigation using same method and equipment and obtains the same results
What is reproducible?
The investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained
What is resolution?
The smallest change in a quantity that an instrument can detect
What is accuracy?
The closeness of a measured value to a standard or known value
What is exponential decay?
A relationship in which a constant change in x gives the same proportional change in the y.
What is exponential change?
A relationship in which the rate of change of the independent variable is proportional to the value of the dependent variable.
What is the general equation for an exponential?
y=kn^x
If 1<n there’s exponential growth
If 0<n<1 There’s exponential decay
What is the exponential decay equation in physics?
y = y ₀e^(- λ * x)
Where λ is the decay constant
As when y = e^x the gradient is equal to the y value.
