This blog is about Simon, a young gifted mathematician and programmer, who had to move from Amsterdam to Antwerp to be able to study at the level that fits his talent, i.e. homeschool. Visit https://simontiger.com
Today we have heard about a new accident involving a teenager electrocuted by her mobile phone. Luckily, this time it was not a lethal case, but a quick search on the web has revealed that this is no joke: several teens have died in just a few years because they were either holding their phone with wet hands while the phone was being charged at the same time, or dropped their phone into the bath tub while the phone was plugged in, or because they were using wired headphones while charging their phone!
At first Simon and I didn’t believe this could be so dangerous, as he knew for sure that a mobile phone adaptor always has a voltage control built into it that reduces the voltage from 220V to something like 5 to 20V. But then we dove into it and found out that apparently, once a short circuit occurs, the adaptor’s voltage control unit also malfunctions and lets the 220V current through!
Simon’s way to celebrate Helloween: a little demo about how red marker reflects red LED light and becomes invisible. A nice trick in the dark!
We also had so much fun with the blue LED lamp a couple days ago when Simon discovered that it projects perfect conic sections on the wall! Depending on the angle at which he was holding the lamp, he got a circle, an ellipse, a hyperbola and a parabola! Originally just a spheric light source we grabbed after the power went out in the bathroom, in Simon’s hands the lamp has become an inspiring science demo tool.
Simon gave me a whole lecture on the differences between Sequential and Combinational Logic: in the former, there’s a presence of a feedback loop (the output actually goes back to somewhere else in the circuit), and the latter has everything going in one direction (the inputs come in and the outputs go out).
It’s a little bit like the difference between a Feed Forward neural network where the output only depends on the input and a recurrent neural network where the output also depends on what the output was previously,
Here’s a problem with sequential logic circuits: they go crazy like this very often (confused NOR gate). That’s why most sequential logic circuits have a clock in them. A clock acts like a delay so that it won’t go crazy.
That’s the power of sequential logic: you can have the same input but a different output. This is useful for storing data: I release the input, but the data is stored. It can only be archived in sequential logic.
The delay comes in error detection (on the rising edge of the square wave).
We have tried using an LED backwards: not get it to shine by letting an electric current pass through it but produce electricity by shining light on an LED (this is how solar panels work). It’s important to use a sensitive LED for this experiment, and as we have observed, it also seems to be important to use light photons of the same frequency as the colour of the LED (red laser didn’t work on a white LED, but it may have to do with the fact that red light is weaker than white light anyway, i.e. has a lower frequency). The picture below shows us measuring the voltage of the current produced by the LED.
We’ve have learned this and a a lot more from Steve Mould’s video on How diodes, LEDs and solar panels work: Photovoltaic cells and LEDs are both made of diodes. Diodes are designed to allow electricity to flow in one direction only but the way we make them (out of semiconductors) means that can absorb and emit light.
In the video, Steve shows how the semiconductor atoms share elctrons. Semiconductors are crystal structures of atoms are replaced by the atoms of neighboring elements, for example a structure where some silicon (Si) atoms are replaced by phosphorus (P) or boron (B) atoms, thus providing for free electrons inside the structure (N-type conductor) or for free “holes” unoccupied by electrons (P-type conductor). A diode is basically two semiconductors pushed together. With enough voltage, the electrones are able to jump from the N-type semiconductor across the depletion zone and into the P-type semiconductor, emitting light (photons) as they fill the holes and go from a high energy state into the low energy state.
If you shine a light at a diode, you can kick some electrons from their shells and thus create free electrons and holes that will move (because of the electric field in the depletion zone) and generate voltage.
If you put a cereal flake in a bowl of water you can steer it with a strong magnet. The magnets above aren’t strong enough, but the really powerful ones below (that are dangerous to pull apart as they can actually injure you) are:
And if you grind the cereal into powder, the powder sticks to the magnet because of the iron atoms in the cereal:
Here Simon tried to induce a magnetic field by allowing electric current to go through a conductor that is normally not magnetic (copper wire). The green stick is a magnet that got attracted to it once the circuit closed.
The copper wire also began to slightly attract the steel paperclips.
For Simon and me, this book (“Infinite Lives of Maisie Day” by Christopher Edge) has probably been one of our most profound experiences of the year. We read it together, sometimes, giggling with joy as we recognized Simon’s favorite topics interwoven in the plot (like that the main character also dreams of proving the Riemann hypothesis), and sometimes tears choking our throats as we went through the sad and scary bits of the story. And what a trip down the memory lane last night, at the Royal Institution in London, where we attended a lecture about the science behind “Infinite Lives of Maisie Day”! As Simon proudly told one of the lecturers (University College London’s cosmologist Dr Andrew Pontzen) after the show, he even predicted something important in the book. Simon recognized that Maisie turned into a mirror image of herself after she had traveled around the Mobius-shaped universe, just as depicted in Escher’s “the impossible staircase” painting . “But that’s only possible if you’re flat, a 2D object! So it’s not correct in the book, but they probably put that in to make it simpler,” Simon laughed. “You’re absolutely right! Keep doing science!” the cosmologist told him. @Ri_Science
Last week Simon suddenly unpacked his old electronics sets and completed several projects with Arduino, his old single-board friend that got him into coding a little over a year ago. Back then it was the most difficult stuff he had ever tried, his first “setups”and “draws”, his first dive into serious circuits. Now Arduino (and iCircuit) is something he does while taking breaks from the real studying/ coding. Amazing how skillful he has become in assembling the circuits, too. All those little wires. Especially considering he still isn’t an expert at tying his shoelaces.
Yesterday Simon asked me to buy new electronics software he found on the internet. It’s a realtime circuit simulator and editor called iCircuit. Simon has already built several circuits in it last night and there is so much more to discover. He was following Derek Banas’ tutorials on electronics.