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# G492 9th June 2016 Discussion - (inc. pre-release)

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1. (Original post by kennz)
My predicted questions for section C (40 Marks)

Dot Plot
Improvement of experiment(2) You want to improve value of x so take more measurements of x or use an electronic ruler or something like that (if it exists) I did a quick google search, you could use a vernier calliper which has a higher resolution - a problem though would be that you could decrease the value of extension because of the way it works. I don't think using a device using a laser/reflection would work effectively though

Systematic error
Question where num of observations is increased which is an improvement (2) As you increase number of observations, then effecct of uncertainty is minimised, e.g. if you take 100 observations instead of 10, the uncertainty is reduced by a factor of 10. I thought repeats don't have an effect on the uncertainty and are only carried out so anomalies are easier to eliminate and for increase reliability..?

Reasonance tube
Label end correction on diagram with anti-nodes and nodes. (1) This is just a regular wave diagram for a closed tube but with the anti-node at the end of the tube 'hanging out' right?
Big question on sytematic error - effect of end correction on final value of speed of sound (4) If we don't account for end correction (by just measuring up to the end of the tube), the measured value of the wavelength will be shorter than it the real value. v = f(lambda). Therefore the calculated speed of sound will be smaller than the actual value. (Is this the answer to the question, or did I misinterpret it?)
See bolded parts
2. (Original post by Fangedbeast)
See bolded parts
Yeah I wasnt sure how to reduce the uncertainty of the extension, Vernier callipers are a good idea, I always thought they were like a micrometer but theyre completely different

In the june 2014 G492 Paper, they did 10 obervations so the uncertainty was reduced by a factor of 10, here look at question 14(a)(ii).
http://www.ocr.org.uk/Images/243756-...a-handling.pdf

Yes you're right about the wave diagram

No I wasnt sure about an answer to this question, to be honest 4 marks would be a worse case scenario, but your answer is really good and would be what I'd say.

Thanks for looking at the questions
3. Will the grade boundaries likely be much higher for this year since there is only A2 students re sitting who should do much better than usual?
4. (Original post by Kichelle)
Will the grade boundaries likely be much higher for this year since there is only A2 students re sitting who should do much better than usual?
If anything, higher. But they could just as well make the paper harder/weird to balance it out enough that it could be the around the same.

(Original post by kennz)
In the june 2014 G492 Paper, they did 10 obervations so the uncertainty was reduced by a factor of 10, here look at question 14(a)(ii).
http://www.ocr.org.uk/Images/243756-...a-handling.pdf
oh... well whatever the mark scheme says i guess
5. (Original post by Fangedbeast)
If anything, higher. But they could just as well make the paper harder/weird to balance it out enough that it could be the around the same.

oh... well whatever the mark scheme says i guess
Yeah i didnt agree with it, but with OCR you just do what they deem as a correct answer and ignore logic
6. (Original post by Kichelle)
Will the grade boundaries likely be much higher for this year since there is only A2 students re sitting who should do much better than usual?
I asked my teacher this she said lower because the majority of students taking it will be those who didn't do very good last year.
7. (Original post by JimJam456)
I asked my teacher this she said lower because the majority of students taking it will be those who didn't do very good last year.
It will be like any other year: souly dependent on the average scores around the country and how hard it was which is reflected in the grades across the country.
It wont be affected by who takes the paper, as even Adults do A-level exams who may have gone to uni and studied stuff but that doesnt make exam grade boundaries high. So, if its a hard paper, the grade boundaries will be lower and vice versa
8. Quick question: if this specification is being scrapped, why did OCR just make a new textbook for it, released last October?
9. (Original post by Polyrogue)
Quick question: if this specification is being scrapped, why did OCR just make a new textbook for it, released last October?
They didnt👀
10. (Original post by kennz)
They didnt👀
Right, but then why are people saying this exam is going to be for retakers only?
11. (Original post by Polyrogue)
Right, but then why are people saying this exam is going to be for retakers only?
New textbook is for the new course. This is the final year of the old.spec so thats why everyone who.is doing it is a retaker. The A-levels from 2015 are reforms for.most subjects
12. (Original post by kennz)
New textbook is for the new course. This is the final year of the old.spec so thats why everyone who.is doing it is a retaker. The A-levels from 2015 are reforms for.most subjects
But my textbook is for this specification, and it was only just published at the end of last year? Thanks.
13. (Original post by Polyrogue)
But my textbook is for this specification, and it was only just published at the end of last year? Thanks.
I very much doubt it, send me a link for the textbook so I can look
14. (Original post by kennz)
I very much doubt it, send me a link for the textbook so I can look
I can safely refute said doubt, since I OWN the textbook, haha.

Here's some images I took of the texbook: http://imgur.com/a/O4RWh
The cover, the contents (with their titles to show it is for this specification), and the inside page stating the publication date, 2015.
15. (Original post by Polyrogue)
I can safely refute said doubt, since I OWN the textbook, haha.

Here's some images I took of the texbook: http://imgur.com/a/O4RWh
The cover, the contents (with their titles to show it is for this specification), and the inside page stating the publication date, 2015.
That's the new specification of OCR B (2015 onward), but the topics are similar to the old specification.

http://www.ocr.org.uk/Images/171729-...ysics-h557.pdf
16. (Original post by Polyrogue)
I can safely refute said doubt, since I OWN the textbook, haha.

Here's some images I took of the texbook: http://imgur.com/a/O4RWh
The cover, the contents (with their titles to show it is for this specification), and the inside page stating the publication date, 2015.
I have no idea then haha, sorry for doubting you
17. (Original post by uk_shahj)
That's the new specification of OCR B (2015 onward), but the topics are similar to the old specification.

http://www.ocr.org.uk/Images/171729-...ysics-h557.pdf
Is that so? But this implies there is literally no change in specification? My teachers advised me to get this book, for use with G49 1,2,4, and 5. And it contains the exact information I need for every topic. If that's the case, the topics aren't similar, they're identical.
18. Good luck guys!
19. Good luck!!!!

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20. How did everyone find it?? Thought it was better than last years but grade boundaries will most probs be higher!

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