Angles of Incidence and Refraction (Ray Diagram)


Light is the reason we can see anything, it reflects off an object and then bounces into our eyes, and voilà  We can see it! Light is the fastest thing we know of – in fact, with any luck, it is the fastest thing that can possibly be – it travels at about 300 million m/s in the air. Now, there are some people (like me!) who can’t see properly without glasses, the light bounces into my eyes the same as you, but it goes wrong there. So, why do we need lenses and how do they work?

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So, what is circular motion? Well: it’s when something moves… in a circle. So, now we’ve covered that, let’s all go back to Facebook and Twitter. Going now! Bye! Oh, wait? You need to know more than that? Like what causes it? Where it’s used in real life? What happens when it all goes wrong?

Well: in that case, you might as well get comfortable…

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Note: for a more in-depth look at circuits, see here!

So, you know all you need to know about circuits, but you’re a bit stuck for how to explain it? Take a look at this simple definitions to help you along:

  • Potential Difference: The amount of energy transferred per coulomb of charge.
  • Current: The flow of electrons in a circuit (they flow from negative terminals to positive terminals!)
  • Resistance: This happens when an electron collides with an atom, and causes heat.

And here’s some helpful things to remember:

Series Circuits:

  • Current stays the same in a series circuit (as the electrons can only go one way)
  • Potential Difference is shared in a series circuit. (Thanks to different resistances)

Parallel Circuits:

  • Current is shared in a parallel circuit (like a fork in the river). The electrons are able to go two or more ways.
  • Potential Difference is the same in a parallel circuit (as the potential difference will always add up again at the ‘end’ of the circuit.

So really, they’re just opposites!


UK Plug Wiring

So, this is it people. After this post, you’ll be able to read and understand the whole AQA P2 Physics specification without ever leaving Revision Systems! It’s taken a lot of words for us to get to this point, but hopefully you’ll find it useful. So, here we go. On this final stretch we’ll be looking at:

  • Plugs (and their wiring, as seen above)
  • Power
  • The dangers of electricity (although these are fairly obvious, so we won’t go into too much detail.)

So, let’s go!

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A/C Oscilloscope Trace

Above this paragraph is a bog-standard oscilloscope trace, from an alternating current (AC) power source. Unfortunately, in the exam, you might be asked to do a bit more than simply look at an oscilloscope trace. That’s why in this article, we’re going to cover what an oscilloscope trace is, what AC and DC are, and the differences between the two.

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Fuse Circuit Symbol

So, what is a fuse? What’s a circuit breaker? How does a fuse work? What’s the difference?! All of these are very relevant questions, and thankfully, all of them are relatively simple to answer, too. For the P2 exam, you need to know what a circuit breaker is, what a fuse is, how they work, when we use them, why we use them, and some advantages and disadvantages. So… Do you have some popcorn? Are you comfortable? If the answer to any of the previous two questions was ‘no’, then you might want to fix that and come back straight away!

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