Changes in charge, current and potential difference during the charging and discharging of a capacitor are all exponential-type behaviours. Specifically, the current that transfers charge to or from a capacitor (during charging or discharging respectively) is always greatest at first and declines to zero as time increases. During discharging, the charge loss and the drop … Continue reading Charging a Capacitor (analysis)
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
How high does a spring toy jump?
Determining a spring toy’s jump height is a useful exercise in the application of physics, not only in terms of this specific example but also in highlighting contrasting approaches to answering any sort of physics question. As is so often the case, there are two possible starting points; the first is theoretical whereas the second … Continue reading How high does a spring toy jump?
How to determine voltages inside a resistor network
Resistor networks sometimes look scary but they can be solved by taking things one step at a time and applying basic circuit rules. The rules concerned are the calculations for combining series and parallel resistors, together with Kirchoff’s two laws for circuits. To combine resistors, we add their values if they are arranged in series … Continue reading How to determine voltages inside a resistor network
The Amateur Scientist
There was a time when children were encouraged to do their own experiments at home. A lucky few got chemistry sets as Christmas presents. Others might have read books covering activities that ranged from star-gazing to building crystal radios. As somebody who grew up in what was probably the golden age for young scientists, before … Continue reading The Amateur Scientist
Beta Decay and Energy Conservation
I have just finished reading an excellent book that traces various theories about beta decay in the first third of the Twentieth Century. Controversy and Consensus: Nuclear Beta Decay 1911-1934 is an editted version of the successful PhD thesis written by Carsten Jensen, who clearly had a deep passion for unravelling physics history but died … Continue reading Beta Decay and Energy Conservation
JMP Summer Challenge 2025
"If you love problem solving, science, or sport, and you're curious about how data analytics and visualization can reveal insights and tell compelling stories, this is the challenge for you. It’s also a great opportunity to stretch your creative muscles and try something new this summer." That is the burb introducing the 2025 Summer Challenge … Continue reading JMP Summer Challenge 2025
Quantum Mechanics: history and mystery
To help celebrate the International Year of Quantum Science and Technology (IYQ) Physics World, the magazine of the Institute of Physics, has compiled a collection of quantum-themed articles. Quantum Briefing 2025 covers "the history, mystery and industry of quantum mechanics" and marks 100 years since Werner Heisenberg formulated the mathematical basis for quantum mechanics while … Continue reading Quantum Mechanics: history and mystery
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
Mr Tarrant's physbang 'blog 