Toy Story and Nostalgia

Fact: When Toy Story's Andy grows up, he is going to resent his mother for "making him give his childhood toys away". Think about it, they represent his growing up. His entire childhood these toys have been growing in collection, forming mental bonds and familiarities. And now they're gone. Given away, as far as Andy knows, under the forced suggestion of his mum, and every time some spot of nostalgia hits him, there will be nothing to quell it. It's not like a grown man can seek out the house of a now, say, mid to late teens girl, and ask whether he can play with his toys for a bit? Just for a bit? I just want to see them. Don't shut the door on me! No! Woody! Woodyyyyy! Woo-Oh hello officer. Why yes there is a perfectly good explanation for why I am screaming woody on this young girls yard.

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On Royals

The Royal Wedding is tomorrow. Aren't you excited? This once in a life time event, this celebration of happiness and two of our future leaders in love? I'm not, as it happens. But it strikes me that there are a whole bunch of people who are.

There are some things that Americans believe about British people. We have bad teeth, we are constantly drinking tea, and we love our royals. We love them. We can't get through the day without singing God Save The [Gender Appropriate Monarchical Title], we embark on yearly pilgrimages to worship our representative of God. Is this true? I certainly don't. No, it seems, and admittedly I have only the perspective of a 20 year old who spends his time with mainly my age group + or - a couple years, that we, to be frank, don't give a damn. Yet curiously, Americans, who hold the belief, themselves seem to love our Queen, and indeed the royal family.

Believeing that we love our royals, and that we live in an Orwellian police state. Oh those crazy Americans.

I have gotten this far in my post and realised that's all I really have. Well, gosh, that wasn't very foresightful of me. In summary then, Americans believe we love the royals but we don't, we believe Americans to be thoroughly engrossed in their own affairs unless it means bombing some other country, but as it turns out, they love our emancipated rulers. Stereotypes are funny things.

But no, I don't much care for the wedding. Even as one who disagrees with the concept of marriage, I am happy for anyone who decides they love someone enough to remain with them til death, however it doesn't really enter into my life. It is just another wedding, though admittedly a fairly grandiose one. There is the possibility that young William will become our future king, but frankly that doesn't really enter into my life either. No, I shall not bother myself with the happenings of tomorrow, beyond wishing their royalnesses the best of luck, a happy future, and thanks for the extra day off college.

P.S. For Christ's sake news media, her name is Katherine, not Kate.

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AS Physics - Matter and Radiation

Ok, today we will be having a quick lesson on particle physics, because while that shit might seem easy, it'll sneak up on you, and you don't want to be let down by one of the most fun parts of A level physics, do you? Aight then, lets do this thing.

First off, the basics you should know. This is only a refresher post, or at least it plans to be, before I inevitably start digging into really interesting but ultimately irrelevant articles. Anyway. Atoms: Really fucking small. Made up of even smaller things called nucleons. These are your garden variety neutrons, protons. They make up the nucleus. Nucleon, nucleus, you see what they did there? Fucking genius. And of course we can't forget electrons. No, those little bastards will come into nearly every aspect of physics ever, somehow.

Now, we all know that protons, neutrons and electrons have charges 1, 0, and -1 respectively, right? Wrong, motherfucker. Those are relative charges. Relative to what? Doesn't matter, because you're now going to forget them. Same goes for those masses of 1, 1, and negligible. In fact, you can super forget them, because they are just plain wrong. No, now we break out the metric, wherein the proton has a charge of +1.6e-19 C (e means x10 to the power of...), an electron has the same, only -ve, and a neutron, well, the neutron still has 0, being neutral and all. Masses are 1.67e-27, 1.67e-27, and 9.11e-31 kg.

Isotopes you should know, atomic symbols you should know...ah, here we go. Basically, after realising that the nucleus was made up of nucleons, physicists considered than maybe something existed that was holding these things together, overcoming the electrostatic force that should be pushing them apart. A force, that effects the nucleons, a nuclear force, if you will. They called this the Strong Nuclear Force, and I have another fun little analogy for you. See, the force only actually works within 3-4fm, and beyond 0.5fm. It's like when you see someone from a distance, and you think "Hey, she's pretty cute. Attractive even!" But then you get a little closer and BLAM. She wasn't nearly as attractive as she seemed from a distance. She is actually kinda repulsive. Got it? Aight. Next song.

Ok, I'm pretty sure we all did radiation in GCSE. Here the only real difference is a small, but important addition to β radiation. When it happens, you get your high speed electron, your atom with +1 proton number, but you also get a neutral antiparticle called an antineutrino, specifically an antiELECTRONneutrino. Because it came with an electron. get it? These were discovered when scientists worked out that in β radiation, energy was being lost. This meant that either Conservation of Energy was bullshit, or another particle was being released here. They went with the latter, since the former had been so good to them in the past, but this went unproven for a further 20 years, when in 1956 there was executed the Cowan-Reines neutrino experiment.

Cowan and Reines used a nuclear reactor, as a source of 5×10¹³ neutrinos per second per square centimeter.

The neutrinos then interacted with protons in a tank of water, creating neutrons and positrons. Each positron created a pair of gamma rays when it annihilated with an electron. The gamma rays were detected by placing a scintillator material in a tank of water. As mentioned in the Discovery of the Nucleus article, and scintillator is a doohickey that flashes, scintillates, when it is hit by something,  in this case gamma rays.

However, this experiment wasn't conclusive enough, so they came up with a second layer of certainty. They detected the neutrons by placing cadmium chloride into the tank. Cadmium is a bitchin' neutron absorber and gives off a gamma ray when it absorbs a neutron.

Most of this paragraph has been ripped from Wikipedia

The arrangement was such that the gamma ray from the cadmium would be detected 5 microseconds after the gamma ray from the positron, if it were truly produced by a neutrino.

Music break! Have one of the greatest pieces of soundtrack music ever composed.

To be honest, you don't need to know most of that shit. I just think it's interesting to know where our ideas come from. Point is we now know that neutrinos are everywhere, even more so than my claimed ability to play the guitar. Billions of them bombard us EVERY SECOND from our very own sun. These are grim days, friends, where our closest ally could also be our gravest threat. But I know that together we can be strong. We will prev--Oh, what, they're harmless? Well never mind then. Next!

Ok, most people know of photons as particles of light. However this is, well, not wrong, just inaccurate. Photons are actually the name given to bursts of electromagnetic waves, which, as you know, visible light is an example of. The idea was established by Einstein when he was working on photoelectricity, where electrons are emitted from metal when light is directed at it's surface, but that's something for another time. For now all you need to know is that LASERS are beams of photons with the same frequency. Note that the energy of a photon is given by hf, therefore is the number of photons passing a point per second is given by n, then the energy per second, i.e. the power of the laser of the specific frequency is given by the simple equation P=nhf.

Ok, here we go. I like this bit because it features a bit of Bristol talent. On 8 August 1902, one Paul Adrien Maurice Dirac was born in Bristol. 26 years later, two years ofter receiving his PhD from Cambridge, the same Bristolian predicted the existence of antimatter. 20 years earlier, Einstein had shown his whole fast particle=more mass thing, relating this with the infamous E=mc². He also said however, that when a particle is at rest, it's rest mass (m) corresponds with it's rest energy (mc²), and that this energy must be included in the conservation thereof. Using this, Dirac predicted that when a particle and it's antiparticle meet, they annihilate. Furthermore, he predicted the reverse, known as pair production, wherein a photon will split into a particle-antiparticle pair, both of which will then piss off from each other. The rest is just maths.

It's kinda difficult to come across image macros that relate to particle physics.

Ok, positrons. Let's do a little on their discovery. They are the antiparticles of electrons, and could just as easily be referred to as antielectrons. Similarly, I suppose, electrons could be referred to as negatrons, and funnily enough, that's what they used to be known as. In short though, a dude called Carl Anderson, one of the more boring names I've ever heard of, was firing beta particles into a cloud chamber. He was then surprised to find that  some trails were actually going in the opposite direction to that he has expected. Exciting stuff. Well, I suppose it was if you were there, but A Level seems to be specifically designed to reduce the most interesting stuff into grey sludge, which is a shame. Physics is such a beautiful subject, filled with elegance and wonderment, and this is lost on a majority of the population who just can't get past how god damn dull the initial learning of it is...Sorry, wrong meeting.

I'm going to leave it there folks. There is more about the weak nuclear force, and Feynmann diagrams, but that last bit kinda depressed me, so I'll leave that to you. Late'.

I was listening to the soundtrack through most of writing this.

(1902-08-08)

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A2 Physics - Capacitors

This is being done on a boat, and as such without internet. Thus I am typing this up in OpenOffice, and without the Blogger Draft's curious ability to know exactly what I want to do with my images. So let's do this thing. Today I will be talking about, oh, lets go for capacitors. I do not like capacitors. So, all the more reason to learn about them, I guess. I shall however be recording my state of boredom through judicious use of reaction images.

This is going to be much more factual than historical, no internet and all, so all I'm working with is my textbook. So let's start with an idea of what a capacitor is. It stores charge. Nothing much else. Get two metal plates near each other, boom, you gots yourself a capacitor. Connect it to a battery blam, you've got a charged capacitor, the two plates actually having equal and opposite charges. This I because the same amount of electrons leave the plates as they do jump on. It's like a water flume. One kid comes out the bottom, the guy at the top pushes another one in. Eventually the first kid gets back to the top of the flume to be pushed down by the guard guy, who I guess in this metaphor represents the battery.

Ok, so, charging one of these bad boys. This can be done by hooking it up to a direct current right? So what we are going to do is stick in a variable resistor, an microammeter, and a voltmeter. Exciting stuff right? Hold on, it gets even better. The voltmeter could be a data logger, which sends data to a computer, about the p.d.. Or you could use a regular voltmeter and use a stopwatch to record the p.d. at regular intervals. Pussy. So now we have some badass information in the form of amperes, p.d., and time. You know what we can do with these? Fucking everything. We want to know how much the capacitor has charged by? Q=It, bitch. We have I, we have t, so you know what that means? Yeah you do you BAMF of a physicist you. We have motherfucking charge Q.

But shit son, there's more. We still got a V hanging around. That's where shit gets interesting. You see capacitors have their own damn quantity called capacitance. This is defined as the charge stored per unit pd. You know what that means? You got it. C=Q/V. We have p.d. V and thanks to our braniac skills above we have charge Q. You know what's coming. Go ahead, tell me, Feel good about it. You got it, we have capacitance C.

And oh shit, you know what? These capacitors are used in tonnes of everyday items, including smoothing circuits, back-up power supplies, timing circuits, pulse producing circuits, tuning circuits and filter circuits. Shit man, this last paragraph is like an electronics student's wet dream.

Ok, so we have the basics. Capacitors are like temporary batteries. And you know what batteries store? Energy. So you know what capacitors store? Energy. Excitement abound. Specifically Electrical potential energy. So, picture this. You have a bunch of electrons on a plate. You know, one of the plates the capacitor is made of. So the plate has a charge, yeah? Then you try to put another electron on the plate. This requires work do be done on the electron/charge. So you put that energy into putting that electron on the plate, and this becomes electrical potential energy. For a comparison, think about gravitational potential energy. You put energy into lifting an object onto a table, thereby giving the object E_GP. Do you get it? Because I kinda do now. This actually feels kinda good.

But how much energy? Consider this in graph form. You mathsy people out there, you know what a graph gives you? Two things, other than the values it already represents. Yeah, the gradient and the area underneath. So now we are going to imagine a graph of charge Q against p.d V. Q is on the x axis and Q and V are directly proportional. You know what that kind of graph looks like I hope. Got it? Good because I'm not going to be mocking up one just for you. Besides, you were already doing so well. Feel free to draw your own if needed. Lets do this. Ok, think in graph terms, we have a capacitor with charge q and we want to add Δq to that value. This is represented on the graph by a vertical strip over Q. This area is the energy required to force that charge onto the plate. (Think of a particularly heavy kid in that water flume).

Excuse me, the original Pokemon theme tune came on iTunes. Just need to rock out.

That was awesome. Where were we? Right. Consider the strip on the graph. Now consider lots of those strips leading to 0Q. The energy still is represented by the area under the graph, but now its hella easy to work out. You know who to work out the area of a triangle? And shit brother, look what we have in that graph. Half base times height that shit, and what do you get? The equation for energy is what. E=½QV. Magic.

Christ I'm bored. And just as we get to the important bit. Charging and discharging these bad boys through a fixed resistor. OkOk, this tenuous metaphor represents the discharging of a capacitor, where the insults and general ill demeanor represent the resistor. So where as before the electron kids were continuous as long as the battery guard kept pushing, the resistor guard just doesn't care. As lots of kids that have built up are now spilling down the flume and possibly over the side of the rails. It's very messy. But the amount of kids falling down slows as there become less of them, and word goes around that this guard may have a thing against kids. Ok, it's not a perfect metaphor.

The point is that the decrease in kids happens exponentially. If we have Q₀ kids at t=0, and then at t=1 we have 0.9 Q₀ then at t=2 we with have 0.9*0.9Q₀, etc etc.

Ok, just a couple more pages. Why is it exponential? Pretty much because some rearranged equations tell us so. Skipping some stuff, some how you end up with ΔQ/Q = -Δt/RC. This tells us that a fractional drop in charge ΔQ/Q is the same in any short interval of Δt during discharge. Rearrange that bastard a bit and you get ΔQ/Δt = -Q/RC. Δx/Δy? Its a differential equation mother fucker! But physicists leave maths to the mathemagicians. We just do some trickery and end up with Q=Q₀ e^-t/RC. Voila. We have created the time constant, RC. Let's just do a final check of my boredom.

Wonderful.

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