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# OCR B G491, 17th May 2012 Morning. Tweet

Physics exam discussion - share revision tips in preparation for GCSE, A Level and other physics exams and discuss how they went afterwards.

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1. Re: OCR B G491, 17th May 2012 Morning.
(Original post by clomitch)
Oh great Yeah I said about it being bunched up and then stretched on the polymer one too, I forgot to talk about the polarising filters! That's probably why it was 3 marks :/ nevermind let's hope for low grade boundaries!
so true!!!
2. Re: OCR B G491, 17th May 2012 Morning.
oh and what did people get for the power dissipated of the resistor in the potential divider?
3. Re: OCR B G491, 17th May 2012 Morning.
i got that too
4. Re: OCR B G491, 17th May 2012 Morning.
(Original post by clomitch)
The bandwidth question I got something like 4.47x10^8? Though that seems very large so is probably wrong.
How were you supposed to answer this question?
Last edited by When you see it...; 17-05-2012 at 12:44. Reason: ?
5. Re: OCR B G491, 17th May 2012 Morning.
(Original post by KoalaKim)
i think i got 100D
Oh yea! so did I, you just jogged my memory I got 99.9D and rouded it to 100D
6. Re: OCR B G491, 17th May 2012 Morning.
(Original post by When you see it...)
How were you supposed to answer this question?
No idea. My method was calculate the number of bits, so I multiplied everything together, and then I remember saying that 2 x max sampling frequency = sampling rate so I divided the bits by 2 to get the frequency? But I was guessing so I doubt it's right!
7. Re: OCR B G491, 17th May 2012 Morning.
(Original post by hihihihihi)
Yeah you had to rearange V=E-Ir forumla and the question was like 3 marks, so whoopppppp
I did that, but I didn't put it in standard form I hope I don't lose marks!

(Original post by Rhiiannaa)
oh and what did people get for the power dissipated of the resistor in the potential divider?
0.072 W
Last edited by Apocalyptic Fish; 17-05-2012 at 12:59.
8. Re: OCR B G491, 17th May 2012 Morning.
(Original post by clomitch)
No idea. My method was calculate the number of bits, so I multiplied everything together, and then I remember saying that 2 x max sampling frequency = sampling rate so I divided the bits by 2 to get the frequency? But I was guessing so I doubt it's right!
In order to find the sampling frequency from the bits per second, you would need to know the bits per sample, which (I don't think) we were told.
Assuming we were told and you calculated the sampling frequency, halving that would give the highest frequency, but that doesn't tell you the wavelength!
Completely baffled as to what they were expecting with that question.
9. Re: OCR B G491, 17th May 2012 Morning.
As usual with this exam section A was okay, then they throw in some crazy questions that have never been seen before and you have to apply your knowledge to something very knew and different, like the bandwidth one which I had no idea how to answer , i tried applying all the formulas and rules related to sampling rate and was utterly stumped
10. Re: OCR B G491, 17th May 2012 Morning.
(Original post by When you see it...)
In order to find the sampling frequency from the bits per second, you would need to know the bits per sample, which (I don't think) we were told.
Assuming we were told and you calculated the sampling frequency, halving that would give the highest frequency, but that doesn't tell you the wavelength!
Completely baffled as to what they were expecting with that question.
Oh well I tried
11. Bandwidth is simple ... Bandwidth is about the same as the bit rate

This was posted from The Student Room's Android App on my GT-I9100
12. Re: OCR B G491, 17th May 2012 Morning.
Well that exam is done never have to do it ever again
13. Re: OCR B G491, 17th May 2012 Morning.
(Original post by engstrom0304)
Bandwidth is simple ... Bandwidth is about the same as the bit rate

This was posted from The Student Room's Android App on my GT-I9100
Really? How many marks will I get if:
I worked out the bits per second;
Didn't write anything on the answer line;
Didn't imply that bits per second was equal to the bandwidth?
1 mark out of 2? Was it even out of 2?
14. Re: OCR B G491, 17th May 2012 Morning.
For the question on the voltmeter attatched to the cell, was it connected in series or parallel. I know that normally they are connected in parallel but for this purpose it would make sense if it was connected in series as that would still work given the high resistance of voltmeters, taking a large proportion of the emf, therefore measuring a value for V close to the value of the cell.
I think I answered the calculations as though it was connected in series (the first one about the resistance of the voltmeter would have been the same either way) but did the explanation as though it was connected in parallel.
Hold on, I'll ask this in the main physics forum.
15. Re: OCR B G491, 17th May 2012 Morning.
(Original post by When you see it...)
Really? How many marks will I get if:
I worked out the bits per second;
Didn't write anything on the answer line;
Didn't imply that bits per second was equal to the bandwidth?
1 mark out of 2? Was it even out of 2?
Yea it was out of 2, i wasn't sure either but I wrote that down in answer so i hope it was right..
16. Re: OCR B G491, 17th May 2012 Morning.
(Original post by hihihihihi)
Yea it was out of 2, i wasn't sure either but I wrote that down in answer so i hope it was right..
Why is bandwidth the same as transmission rate? Can anyone explain it?
17. Re: OCR B G491, 17th May 2012 Morning.
can someone please do an unofficial mark scheme coz im still worried that ive done worse than before when i did it first time in jan and was the last Q the 4 mark sunglasses question coz i remember there was a blank page after that and wasnt sure if there were other questions ive missed out..
Last edited by ila4e123; 17-05-2012 at 17:41.
18. Re: OCR B G491, 17th May 2012 Morning.
(Original post by When you see it...)
I think I got about 45 - 50 raw marks.
What do you think the grade boundaries will be like? Did you find it easy/hard?
I personally thought that it was harder than many past papers (then again, everyone always thinks that the exam they sit is the hardest ever) although at the same time fairer than the others.
Well I thought I was screwed seeing as I was getting in the range 29-42 out of 60 on past papers, which I actually found extremely hard, but this exam was easier than any of the past papers I've done and I found the past ones hardly contained anything that was even on the course...
Most of my classmates feel the same although some found it really hard. I certainly didn't find it easy, just easier than the other ones
19. Re: OCR B G491, 17th May 2012 Morning.
Just went through the paper with my teacher and I should have 50-55 marks looking at 54 from what I have told my teacher!!

Do you think that will be enough for 90 UMS? It has been before but recently the grade boundaries have been gradually increasing. Anyway as long as I have 83+ UMS I will be happy. Ahh not bad for a year 11

Btw what did you guys get for the bamdwidth question because I got it wrong and my teacher said bandwidth is the bit rate yet I don't even remember learning that!
20. Re: OCR B G491, 17th May 2012 Morning.
(Original post by GreenLantern1)
Just went through the paper with my teacher and I should have 50-55 marks looking at 54 from what I have told my teacher!!

Do you think that will be enough for 90 UMS? It has been before but recently the grade boundaries have been gradually increasing. Anyway as long as I have 83+ UMS I will be happy. Ahh not bad for a year 11

Btw what did you guys get for the bamdwidth question because I got it wrong and my teacher said bandwidth is the bit rate yet I don't even remember learning that!
Wow. Well done!
For the question with the voltmeter being used to measure EMF, did your teacher say that it was connected in series or parallel?
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