How to Combine Uncertainties
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 or subtracting quantities then the…
Read moreCoulomb’s Law and Nuclear Radii
Estimating the size of a nucleus using electrostatic repulsion can be traced back to the invention of an ultra-sensitive apparatus, which measured forces in terms of the twisting of a fine wire, dating from the 18th Century. This device, known as a torsion balance, is often attributed to the French engineer and physicist Charles Augustin de Coulomb but may well…
Read moreRequired 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 relationship that is being investigated.…
Read moreSolar Eclipse, 12th August 2026
Next Wednesday, 12th August 2026, a full solar eclipse will be visible from Iceland and Greenland in the north, together with Spain and the very north-eastern tip of Portugal in the south. In Jersey, the eclipse will cover more than 90 percent of the Sun’s surface at around 7:15pm. Weather permitting, it should be quite a spectacular sight. Much of…
Read moreHubble Tension Part 2: Baryon Acoustic Oscillations
There is an introduction to the nature of the “Hubble tension” in the first part of this article, which covers measurements based on the distance ladder (see https://physbang.com/2026/07/28/hubble-tension-part-1-the-distance-ladder/). This article looks at how the Cosmic Microwave Background (CMB) can be used to calculate the expansion of the Universe – and therefore the Hubble constant. But first it is useful to…
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