Measurements are always subject to some uncertainty. The minimum uncertainty is set by the resolution of the device used but repeated measurements may reveal a range of readings, which is more significant than the instrument resolution when determining uncertainty. In A-level Physics calculations, uncertainties are combined using two simple rules; If the calculation involves adding … Continue reading How to Combine Uncertainties
Required Practicals, Part 1: Planning
This is the first instalment in a short series looking at the qualities that characterise a high-quality report for an A-level Physics required practical. First up is planning, which has to be conducted in advance to ensure that the most appropriate apparatus and methods are used. Proper planning documentation must identify the variables and the … Continue reading Required Practicals, Part 1: Planning
Instrument resolution and experimental accuracy
Uncertainties in measurements arise from the equipment used and the method employed. As the final paper for this year’s A-level Physics examination is imminent, and tests knowledge of uncertainties, it is worth taking a moment to examine the causes of uncertainty in more detail. We will do this by thinking about two example measurements; one … Continue reading Instrument resolution and experimental accuracy
Know your calculator!
When answering examination questions, it is important that your excellent knowledge of physics isn’t undermined by your calculator behaving in an unexpected way. You MUST be able to trust the answer given. But the situation is potentially complicated, not only because calculators don’t all behave the same way but also because they may not even … Continue reading Know your calculator!
Uncertainties and Error Bars
Measurements are always uncertain: there is no such thing as a perfectly precise measurement. At the very least, the instrument used will limit the precision of the value but in many cases other factors can introduce even greater variability. It is always the greater of these two numbers (the resolution of the instrument and variability … Continue reading Uncertainties and Error Bars
Revision tips for Paper 3A
It’s a fool’s game to try to predict what will be in an examination paper but… looking back over past years, there are three practicals that have been used very little in Paper 3A and one of those hasn’t appeared since 2020. So, in my opinion, there is a good chance that this year’s paper … Continue reading Revision tips for Paper 3A
How to read Vernier callipers
Having previously discussed micrometers as instruments that some people find tricky to read (see https://physbang.com/2025/04/09/how-to-read-a-micrometer/) we now come to the instrument that many people find even more difficult; Vernier callipers. Whereas micrometers are mostly used for measuring thicknesses between flat surfaces, callipers are better when the surfaces are curved. In particular, callipers are commonly used … Continue reading How to read Vernier callipers
Random and Systematic Errors
Two previous posts covered uncertainties in the context of thermal energy transfers but now we need to consider random and systematic errors as they apply more generally in the current AQA A-Level Physics course. NOTE: The AQA A-Level Physics syllabus takes a simplified approach to uncertainties so if you are doing independent revision you may … Continue reading Random and Systematic Errors
How to read a micrometer
Being able to take measurements using common items of instrumentation is an expected skill for A-Level Physics and can be tested in examinations using diagrams or photographs. This post is the first in a short series that will look at measurement skills, starting with a piece of equipment that often causes difficulties; the micrometer. To … Continue reading How to read a micrometer
Paper 3a, Q3 walk-through
This post completes an explanation given to my current Y13 students, which was unfinished at the end of our lesson. It relates to the second half of Q3 in Paper 3a for the AQA A-Level Physics examination of June 2023. You can download a copy of the complete paper here. To solve Q3.4 you must … Continue reading Paper 3a, Q3 walk-through
