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# AQA Physics Unit 1 PHYA1 20th May 2013 watch

1. I love the quantum phenomena topic for this unit, but I have never been able to get my head around Feynman diagrams or interaction and I just find electricity a real chore to revise. Which sucks cause I really need an A by the end of this year
2. (Original post by Felix Felicis)
Ok, so you can work out the total resistance to be

Now, when the voltage branches off into the 2 parallel branches, the voltage stays the same (each coulomb of charge still has the same amount of energy) but the current splits as the charges split. Call the current across A-E and the current across B-F

From conservation of energy, you know that the potential difference (i.e. the voltage drop) across A-E has to be 12V as when the current branches from E and goes back to the cell, there should be a drop of 12J in every coulomb of charge, therefore you know that by Ohm's law

Thus, the potential difference across A-C is

By similar arguments, you can calculate the potential difference across BD and the difference in C-D is just the difference in potential difference from AC and BD.
You again! :P

Are you even doing this exam? haha

But thank you- that was a really useful explanation

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3. Any advice for the electricity diagram questions?

Is it just: a) be able to draw potential divider circuits; b) be able to draw variable resistor circuits; c) always have an ammeter in series, and a voltmeter in parallel, with whatever you're measuring. Anything else?
4. Can someone give a simple explanation of why there is a maximum value for Ek in the photoelectric effect?

Thanks
5. (Original post by Alistair_Mallard)
Anyone got any bets on what the long answer question will be on?
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me
6. What sort of things are on every 6-mark experiment question's mark scheme? Such as taking repeat readings, etc.
7. (Original post by x-Sophie-x)
You again! :P

Are you even doing this exam? haha

But thank you- that was a really useful explanation

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Me again...

Lolno, OCR ftw. xD But I'm bored from my chem/ geog revision and decided to go on TSR considering I'm gated. xD I see physics question, I do random physics question => Monkey see, monkey do....xD

No probs
8. (Original post by danlocke)
Can someone give a simple explanation of why there is a maximum value for Ek in the photoelectric effect?

Thanks
Photons have energy dependent on frequency. Each electron absorbs the energy from 1 photon and therefore gains energy = hf, where hf is the energy of a light photon. An electron can leave the metal surface if the energy gained from a single photon exceeds the work function of the metal. therefore, the maximum ke of emitted electron is given by ek=hf-work function. (The intensity does not effect the max ke of a photoelectron). No matter how intense the light is, the electron will still absorb 1 photon, and there gains max kinetic equal to hf-work function.
9. (Original post by BenChard)
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me

Internal resistance experiment though? never come up, and surely thats a contender?
10. (Original post by BenChard)
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me
They won't ask exactly the same question and theres no other reasonable questions to ask about osciloscopes
11. (Original post by Goods)
They won't ask exactly the same question and theres no other reasonable questions to ask about osciloscopes
I think the same.
And I seriously hope it isn't oscilloscopes..I hate them.

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12. anyone got a link to the jan 13 paper ?
preferably mark scheme to
13. (Original post by BenChard)
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me
if it is another oscilloscope question i will cry into my hands
14. (Original post by vengeance111)
anyone got a link to the jan 13 paper ?
preferably mark scheme to
http://www.thestudentroom.co.uk/show...age=22&page=22 end post
15. (Original post by Alistair_Mallard)
Internal resistance experiment though? never come up, and surely thats a contender?
earlier in the thread I did suggest it could be a question on emf and internal resistance, just internal resistance would be too easy simply connect an ohmmeter to the battery

(Original post by Goods)
They won't ask exactly the same question and theres no other reasonable questions to ask about osciloscopes
fair point I know my oscilloscopes inside out just In case. most likely is emf and internal resistance from a graph or possibly work function and threshold frequency from a graph.
16. (Original post by BenChard)
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me
Could possibly well be an oscilloscope :P
17. Doing this paper and it's asked for energy but it's got answer in Watts, is that a mistake because I thought energy is in Joules

http://filestore.aqa.org.uk/subjects...W-QP-JUN11.PDF Question 6 d)ii
18. (Original post by carrellii)
I love the quantum phenomena topic for this unit, but I have never been able to get my head around Feynman diagrams or interaction and I just find electricity a real chore to revise. Which sucks cause I really need an A by the end of this year
Here are the 6 feyman diagrams you need to remember.

19. (Original post by Qari)
Doing this paper and it's asked for energy but it's got answer in Watts, is that a mistake because I thought energy is in Joules

http://filestore.aqa.org.uk/subjects...W-QP-JUN11.PDF Question 6 d)ii
Energy is Joules and power is joules/second. watt is another name for power.
20. (Original post by BenChard)
last year: oscilloscope
year before: circuit
year before: circuit
year before: circuit
year before: photoelectric
year before: photoelectric
year before: photoelectric

it is screaming out to be another oscilloscope to me
I just feel like its gonna be another one on circuits, something on a filament lamp hasn't come up before

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