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
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
Experimental Errors (part 2)
The previous post (Experimental Errors, https://physbang.com/2023/11/12/experimental-errors/) ended with an invitation to "consider whether there are any other, previously unidentified, sources of uncertainty" in the method used to derive the specific heat capacity of an iron block. As it happens, there are (at least) three possibilities that weren't covered in the original article. Firstly, there is … Continue reading Experimental Errors (part 2)
Experimental errors
Experiments are often used to confirm (or, more usefully, refute) particular ideas but their impact is limited by measurement errors that can compromise the results. The obvious answer is to reduce the uncertainties as much as possible but what do you do if this causes the result to move further away from the expected value? … Continue reading Experimental errors
Measuring Speed
This is the third part of a mini-series looking at motion and here we’ll be considering different ways to measure speed as well as some common sources of error. In theory, speed is easy; we just need a distance (measured using a ruler, for example) and a time (probably measured using a stopwatch but ideally … Continue reading Measuring Speed
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