The act of making a measurement changes the measurement being made.
Category Archives: Physics
Every action has… no, I cannot finish that
Newton’s Third Law. Need I say more? Well, in this weblog post, I say a lot more.
On the phases of ice
The Eskimos have hundreds of words for snow, or so they say, but what about ice Think ice is simple? Think again!
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.
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! https://youtu.be/nEY3OsCPZtU If there’s anything you need helpContinueContinue reading “Internal resistance and delivering the maximum power to a load resistor”
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 afterContinueContinue reading “More fun with op amps: differentiation”
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.
Fun with Op Amps
One can see the same potential applied to both inputs of the op amp, causing 0V output potential. That made sense. When connecting the inverting input pin to half the potential of the output (using two 10 kΩ fixed resistors as a potential divider), the output potential became 10V. Well, half of 10V is 5V, so that would make the inverting input potential 5V, the same as in the first case, yet the output potential is different.
Not the aurora after all
Whilst I’m sure it was still impressive and exciting looking at ‘rainbow clouds’, it was a big let down compared to the prospect of looking at an aurora this far South.
Physics with Keith 