The Water Cycle

Ah, the… Wait, the what?

The water cycle describes the movement of water through the environment

And it’s as simple as that.

(EDIT: We’ve had it pointed out to us that this isn’t on the newest specification, which is the case – so don’t worry about learning this, but we’re going to leave the article, as it’s still a nice thing to know, right?)

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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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Current electricity and calculations involving electricity within different types of circuit are important for P2 – so of course, we’re going to cover it here. Ready? Then let’s dive into the wonderful world of electricity…

Note: Check out Ben’s article on circuit symbols here for a supplementary article: http://www.revision-systems.co.uk/symbols-used-in-an-electrical-circuit/

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An Exothermic Reaction

Right, this is going to be a really quick post for a pretty short topic!

Here’s the basics: when chemical reactions occur, energy is transferred (because energy is required to break and make bonds). Two things can happen in this case: either the reaction ‘gives out’ heat (energy) to its surroundings, or it ‘takes’ heat (energy) from its surroundings. We have two special terms for these events:

  • Exothermic – This is when the reaction ‘gives out’ energy, in the form of heat. Think of it as heat exiting the reaction (or alternatively, just learn the two different definitions – there are only two after all…
  • Endothermic – You guessed it – this is when the reaction ‘takes’ (usually heat) energy from the surroundings, for its own devious purposes. You could think of it as energy entering the reaction.

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