Numbers
AQA AS-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Measurements and Their Errors
- 3 subtopics
- 16 things to know
- Papers 1 and 3
What Measurements and Their Errors covers
Measurements and their errors runs through the whole course and can be examined on any paper. It covers the SI system, how uncertainty is calculated and combined, and how to estimate a quantity to the right order of magnitude.
Where it is assessed
Papers 1 and 3
Core content, then practical skills and data analysis.
Check the AQA specification ↗The 3 subtopics
Each one has its own page. AQA AS Physics students sit this topic in the first year.
- Use of SI units and their prefixesThe base units, how derived units are built from them, and converting between prefixes.Open →
- Limitation of physical measurementsRandom and systematic error, precision and accuracy, and combining absolute and percentage uncertainties.Open →
- Estimation of physical quantitiesWorking to an order of magnitude, and estimating a derived quantity from known values.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
How are derived units formed, and what do the prefixes tera and giga represent?
Numbers
What does the prefix milli mean, and how do you convert millimetres to metres?
Numbers
Why use kilowatt-hours instead of joules, what is one kilowatt-hour worth, and how many kilowatt-hours is 4.46 × 10⁷ J?
Evaluation
What are absolute and fractional uncertainty, and what does accuracy mean?
Evaluation
How is percentage uncertainty found, and how do uncertainties combine when adding?
Evaluation
How do uncertainties combine when quantities are multiplied, divided or raised to a power?
Evaluation
How are the extreme lines of best fit used to find uncertainty in a gradient?
Evaluation
How is gradient uncertainty calculated, what is a zero error, and how can it be corrected?
Evaluation
Why are absolute uncertainties added when two measurements are subtracted?
Evaluation
How do you combine uncertainty for a square root, and how many figures should you quote?
Numbers
When two measurements are multiplied together, how do you combine their uncertainties?
Process
When two measurements are added together, how do you combine their absolute uncertainties?
Numbers
How is the order of magnitude of a derived quantity estimated?
Numbers
Where does the boundary between adjacent orders of magnitude lie, and why?
Key term
What does it mean to estimate a quantity to the nearest order of magnitude?
Take Measurements and Their Errors further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Accuracy vs Precision
Accuracy: closeness to the accepted value. Precision: closeness of repeated readings to each other.
Random error vs Systematic error
Random error: unpredictable variation causing scatter. Systematic error: consistent bias shifting readings in one direction.
Absolute uncertainty vs Percentage uncertainty
Absolute uncertainty: uncertainty expressed in measurement units. Percentage uncertainty: uncertainty expressed relative to the measured value.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the SI base unit for mass, and what is its symbol?
Model answer
The kilogram, symbol kg.
- 2
What is the SI base unit for amount of substance, and what is its symbol?
Model answer
The mole, symbol mol.
- 3
What is the SI base unit for electric current, and what is its symbol?
Model answer
The ampere, symbol A.
- 4
How are SI derived units formed from fundamental units?
Model answer
By combining fundamental units through multiplication or division.
- 5
What power of ten does the SI prefix tera (T) represent?
Model answer
10¹².
- 6
What power of ten does the SI prefix giga (G) represent?
Model answer
10⁹.
What is inside Levo
Six ways to work the same material.
Measurements and Their Errors revision questions
- Is Measurements and Their Errors examined at AS in AQA Physics?
- Yes. It sits in Papers 1 and 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Measurements and Their Errors cover in AQA AS-Level Physics?
- 3 subtopics: use of si units and their prefixes, limitation of physical measurements and estimation of physical quantities. Each one has its own page with questions and model answers.
- How is Measurements and Their Errors organised?
- By the AQA 7408 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Measurements and Their Errors, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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