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OCR PHYSICS B G491~ 19th May 2015 AM ~ AS Physics Watch

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    (Original post by luke_bishop)
    Does anyone have any resources to help with resolution and pixel questions?
    What sort of thing do you need? Equations, or just general notes?
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    (Original post by AndrewC19)
    What sort of thing do you need? Equations, or just general notes?
    Equations and general notes, guides through exam questions, e.g. G491 June 2011 Question 8.
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    Just a quick question, why did everyone hate last year's paper? I did it as a mock and honestly I thought it was better than some of the previous papers.
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    I'm revising so much but I have no confidence whatsoever. Which teacher thought it would be smart to choose OCR B Advancing Physics? There's a reason no one does this exam board and that's because it's ****
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    (Original post by IrfanR)
    I'm revising so much but I have no confidence whatsoever. Which teacher thought it would be smart to choose OCR B Advancing Physics? There's a reason no one does this exam board and that's because it's ****
    I agree! What in this course is so compelling to teachers to chose it over every other better course? Because the book is ****ing useless ( haven't opened it since september) and the exams can be random
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    (Original post by Fandalf)
    I agree! What in this course is so compelling to teachers to chose it over every other better course? Because the book is ****ing useless ( haven't opened it since september) and the exams can be random

    I've been sat on my ass all day revising. I am learning a little but the process is so slow and I feel so helpless because I have Maths, Chem and Bio to revise for as well

    and don't get me started on the book…

    Do you have any topics your particularly not fond of?
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    (Original post by IrfanR)
    I've been sat on my ass all day revising. I am learning a little but the process is so slow and I feel so helpless because I have Maths, Chem and Bio to revise for as well

    and don't get me started on the book…

    Do you have any topics your particularly not fond of?
    Hey we have the same horrible schedule. I think. Do you have 4 days where you have an exam a day? Also yeah, I generally hate everything about unit 1, maybe with the exception of waves
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    (Original post by Fandalf)
    Hey we have the same horrible schedule. I think. Do you have 4 days where you have an exam a day? Also yeah, I generally hate everything about unit 1, maybe with the exception of waves
    Yes! xD You took all sciences and maths as well? 19th, 20th, 21st, 22nd
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    (Original post by IrfanR)
    Yes! xD You took all sciences and maths as well? 19th, 20th, 21st, 22nd
    Yep. Good luck to us all. Some of us may die in battle but hopefully most of us will make it to see the dawn of a new day, a day with nice grade boundaries...who am i kidding I'm gonna fail
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    (Original post by luke_bishop)
    Equations and general notes, guides through exam questions, e.g. G491 June 2011 Question 8.
    I've worked through the answers for you logically so you can see how to approach the question, it's easy as long as you understand what the question is asking of you.



    8a). Number of bits = log2(number of levels) = log2(128) = 7 bits/level

    8b). Total pixels = 700*520= 36400 pixels. -> 36400*7 (as 7 bits per pixel) = 2548000 bits = 318500bytes ~ 0.32Mbytes < 1Mbyte

    8c). 2.6cm = camera to Endeavour 0.7cm = camera to Atlantis
    2.6/0.7 = 3.71 = 3.7:1 ratio as ratio = Distance to E/Distance to A

    8d). i - Atlantis = 2.6 cm Length of image = 9.3 cm 2.6/9.3*520 ~ 145 pixels
    Length = 145 * 0.24 = 35m tall.

    ii - Ratio from part c -> 0.24*3.7 = 0.89
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    (Original post by luke_bishop)
    Equations and general notes, guides through exam questions, e.g. G491 June 2011 Question 8.
    Here's a page of all equations that aren't in the formula book that you may need for G491.
    Attached Files
  1. File Type: docx Formula.docx (12.7 KB, 213 views)
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    (Original post by DarkMask09)
    In one of the previous physics threads, I found a few quite promising links including...

    http://sam.davyson.com/as/physics/cards/ (This guy is amazing!)
    http://en.wikibooks.org/wiki/A-level...ncing_Physics) (Everyting is split up into their individual parts.)

    Hope these help with your revision. I'm really starting to panic about the test.:afraid:
    Cheers! We got given the wikibooks stuff in class but some stuff is still mental! I must admit I'm in a panic now too... Just hope they're nice to us this year D:
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    how to people approach significant figures for this exam?
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    how do people approach significant figures for this exam?
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    (Original post by jpetersgill)
    how do people approach significant figures for this exam?
    What I generally do is use whatever significant figure the question uses. Sometimes it gives you two values with different ones, both are fine, but I generally like to stay for the lowest. Most of the time (I think) they tend to keep to 2sf. Does anyone else have a different way...?
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    Most mark schemes do seem to prefer 2sf for most questions, unless specified otherwise. They tend to condone 3sf if the answer is inexact or exact, but any more than 3sf for an 'inexact' answers i penalised (specifically stated in the may 2011 examiners report and mark scheme).
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    Ive made something for each unit of the physics in action paper that gives all of the key formulae and keywords if anyone wants it? I'll be happy to if your emails are messaged to me
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    Hi! It says in the spec for materials section we need to know "direct evidence of the size of particles and their spacing" Probably being stupid but what is this!?! Also what equations do we need to know for materials that aren't on the formula sheet? Thanks so much!


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    (Original post by razzmataz1478)
    Also resitting. The last question in last years' paper was ridiculous. And practically impossible given the great amount of thought it required and the time constraint. I think this year's paper will be slightly easier, as I know a lot of teachers were complaining about it when they had that briefing for the new spec some time ago; hopefully OCR officials overheard them.

    (Original post by HennersPD)
    I'm resitting also and wondered if anyone has done the g491 paper from may 2014 and what they thought about the lenses questions as these confused me! Also do you think this years paper will be easier or not? Is this the last year for the G492, G494 AND G495 papers?
    Just in case you still didn't get what the last question on G491 June 2014 was about, I typed up my mock answer for it for someone the other day and it is below. Hopefully it will help you

    To be honest I don't think there is too much of a time constraint. Sure, the question was a difficult one, but I for one managed to fit it in and then could do about 15 minutes of checking over (I admit, I am rather fast at doing question papers, but even so). Hopefully this papers will be nicer though (but retain the low grade boundaries )

    I was just wondering if anyone had any good websites for the materials stuff. I keep forgetting the terms like grain boundaries and definitions for things like strength.



    Spoiler:
    Show
    Magnification = Image length / Object length.
    As the object is 2.5m away, we convert this to mm and get 2500mm, The image length is the distance to the image being formed, which is given in the question as 5mm.
    The magnification is therefore 5/2500 = 0.002.

    This means that we can work out how big the image will appear on the CCD - this time we use
    Magnification = Image size / Object size.
    Here the magnification is the same as above and the object size is 33mm.
    Therefore the image size = object size (33) * magnification (0.002) = 0.066mm.

    * the stuff above this point is basically the same as in i and ii. *

    As the CCD has 1000 pixels across and the image is 2mm then we calculate that the size of a single pixel is;

    2/1000 = 0.002mm

    This means that each pixel is 0.002mm along. Given that the image formed on the CCD is 0.066mm we can then see that if you divide it by 33 (number of modules along width of the QR code) we get 0.002mm for each module in the dot.

    This means that each module takes up exactly 0.002mm which is the exact same size as the pixels on the CCD. If the QR code was any further away then the magnification would be lower, so the image size would be lower and the size of each module on the image would be lower than the size of the pixels, so it would not be visible.
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    Guys i don't understand the graphs of resistors, for example Question 1 on http://www.ocr.org.uk/Images/175463-...-in-action.pdf Can someone please explain it to me ? thanks :confused:
 
 
 
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