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2016 | OCR A2 Advancing Physics B | G494 & G495 | 20th & 28th June

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Reply 160

WhiteBison

Original post by irrationalvarun

Bye! And good luck with what exam you're having! (I'm having C3 tomorrow so I'm not at all worried about it)

I'm the same. C3 so should be smooooth sailin'.
Good luck with yours mate.

Reply 161

Kristofa

Where's the difficulty poll at? I wanna know how other people did so I feel less bad about how badly I did and know I'm oh the only one hopefully lol

Reply 162

smartalan73

Original post by Matt309

I got 170000pa too or 17000pa I cant remember

I actually got 117000 but its wrong, you were supposed to do some stuff and end up with 17000 then you were supposed to subtract it from 100000 but I added, guessing you either did the same or just left it. I'm sure we'll still get some marks for it.

Reply 163

Stefan98

Who's ready for g495? I most definitely am not!

Reply 164

WhiteBison

Original post by Stefan98

Who's ready for g495? I most definitely am not!

FML I have FP2 Maths the day before so I have very little time to go over it. xD
But the papers I've done previously were fairly good so hopefully we'll make do!

Reply 165

Stefan98

Original post by WhiteBison

FML I have FP2 Maths the day before so I have very little time to go over it. xD
But the papers I've done previously were fairly good so hopefully we'll make do!

That sucks. How did you find g494?

Reply 166

WhiteBison

Original post by Stefan98

That sucks. How did you find g494?

I think it went well, but I didn't think it was an especially easy paper by any means - though I've heard both extremes (as is always the case). You?

Reply 167

danthebox

anyone got anymore questions on the pre release material?

Reply 168

Stefan98

Original post by WhiteBison

I think it went well, but I didn't think it was an especially easy paper by any means - though I've heard both extremes (as is always the case). You?

I'm the same really. I found it decent but some people said it was really hard so yeah you can't tell

Reply 169

Polyrogue

Right, now to understand the entirety of G495 + the anm in three days :biggrin:

Reply 170

Fangedbeast

Original post by Polyrogue

Right, now to understand the entirety of G495 + the anm in three days :biggrin:

yup

edit: do we need to know about Feynman diagrams? If so, how in depth do we need to understand it? I remember doing like half a lesson on it

(edited 7 years ago)

Reply 171

Polyrogue

Original post by Fangedbeast

yup

edit: do we need to know about Feynman diagrams? If so, how in depth do we need to understand it? I remember doing like half a lesson on it

googles Feynman diagrams

I have never seen this before, so I don't think so, or at least not in any great detail.

...I hope so, at least.

Reply 172

Stefan98

It's not on the spec but my teacher said it helps people remember things like proton decay ect. I don't think we'll be asked to draw them but it could help you remember the stuff easier

Reply 173

Obi-Wan

In the pre release article, why can't another cable be added to complete the circuit? And how is this method not generating electrical energy from nothing?

Reply 174

carysholland

Original post by Obi-Wan

In the pre release article, why can't another cable be added to complete the circuit? And how is this method not generating electrical energy from nothing?

I think adding another cable would interrupt the flux cutting of the first cable, so emfs would be enduced on both and so it wouldn't make a circuit. Not sure if this is the exact reason, but it's definitely something to do with a second cable also cutting flux line

Reply 175

kennz

Original post by Obi-Wan

In the pre release article, why can't another cable be added to complete the circuit? And how is this method not generating electrical energy from nothing?

An electrodynamic tether can be described as a type of thermodynamically "open system". Electrodynamic tether circuits cannot be completed by simply using another wire, since another tether will develop a similar voltage. Fortunately, the Earth's magnetosphere is not "empty", and, in near-Earth regions (especially near the Earth's atmosphere) there exist highly electrically conductive plasmas which are kept partially ionized by solar radiation or other radiant energy. The electron and ion density varies according to various factors, such as the location, altitude, season, sunspot cycle, and contamination levels. It is known that a positively charged bare conductor can readily remove free electrons out of the plasma. Thus, to complete the electrical circuit, a sufficiently large area of uninsulated conductor is needed at the upper, positively charged end of the tether, thereby permitting current to flow through the tether.

However, it is more difficult for the opposite (negative) end of the tether to eject free electrons or to collect positive ions from the plasma. It is plausible that, by using a very large collection area at one end of the tether, enough ions can be collected to permit significant current through the plasma. This was demonstrated during the Shuttle orbiter's TSS-1R mission, when the shuttle itself was used as a large plasma contactor to provide over an ampere of current. Improved methods include creating an electron emitter, such as a thermionic cathode, plasma cathode, plasma contactor, or field electron emission device. Since both ends of the tether are "open" to the surrounding plasma, electrons can flow out of one end of the tether while a corresponding flow of electrons enters the other end. In this fashion, the voltage that is electromagnetically induced within the tether can cause current to flow through the surrounding space environment, completing an electrical circuit through what appears to be, at first glance, an open circuit.

copy and pasted from wikipedia :biggrin:

Reply 176

Robert2798

Anyone know how accurate the Matthew Arnold questions are for the advanced notice material, like have some of their predicted questions for past years come up in previous section C's or are they just useful questions to do to further the understanding of the advanced notice material?

Reply 177

danthebox

Original post by Robert2798

yeah last year on G492, some questions came up that matthew arnold school had made up, but they weren't EXACT, like the questions gave you some extra random info, which the prerelease didnt contain.

Reply 178

Robert2798

Original post by danthebox

yeah last year on G492, some questions came up that matthew arnold school had made up, but they weren't EXACT, like the questions gave you some extra random info, which the prerelease didnt contain.