-
Bye bye Patreon, bye bye Discord…
While I was redesigning my website (i.e. procrastinating from doing my marking) I noticed that it was possible to make certain blog posts that could only be seen to paying subscribers. I also noticed that it was possible to make parts of pages visible only to paying subscribers too. WordPress, who hosts my website, had…
-
Five questions A-Level physics does not answer
Students often choose to study A-Level Physics because they want to understand how the universe works. GCSE Physics has lots of gaps, but surely Advanced Level Physics will have the answers? Here are five intriguing mysteries that A-Level Physics does not answer.
-
Lamenting the loss of the sound of silence
I find it difficult to focus my attention on a single voice and hear what someone is saying to me if there is any background noise. Years ago I had my hearing tested and it was fine, it wasn’t a hearing issue. It is just something about the way my brain processes sound. For yearsContinue…
-
The fascinating etymology of the word ‘diode’
Diode = two way… what an odd name for a component that allows current to flow just one way. Where did this name come from? I’ll explain all in this blog post.
-
Internal resistance and delivering the maximum power to a load resistor
I was teaching this on Friday but ran out of time to go through the calculus with my class, so here is a quick(ish) video about why you get the maximum power delivered when you match the load resistance to the internal resistance. Hopefully you find it useful! If there’s anything you need help withContinue…
-
A Level revision timetable!
I’ve written a spreadsheet that creates a revision timetable automatically – just plug in the topics and off you go. It includes interleaving and repetition to promote long term retrieval. Here’s a screenshot (the colours are for broad topics): This is available to enrolled A Level tutees, and there’s a GCSE version available to enrolledContinue…
-
Looking inside the HP 9820A calculator
I was very kindly and generously gifted a Hewlett-Packard HP 9820A calculator by a good friend and ex-colleague. Unfortunately, the thing does not work, but I will try to get it working when I find the time between other things I have to do. The HP 9820A was the world’s first calculator that used anContinue…
-
More fun with op amps: differentiation
Yes, I finally managed to get an op amp to differentiate an input potential that varies over time. The top trace is the input potential. The bottom trace is the output from the op amp, showing the first derivative of the input. Huzzah! I connected the differentiator circuit to a sinusoidal input potential, and afterContinue…
-
How to analyse circuits using superposition
Analysing circuits with two different power supplies can be tricky. There are a few approaches one can take. In this video, I show firstly how Kirchhoff’s Laws can be used with simultaneous equations to brute-force answers, and how to take a slightly more elegant approach by using the principle of superposition.
-
Physics with Keith
Interactive online physics tuition for GCSE/IGCSE and A-Level students (and equivalent) by an experienced and qualified physics teacher.
Social Media
Ⓒ 2026 by Keith Dalby
Physics with Keith 