ANSWERS: OCR Physics B(Advancing Physics) G491~ 20th May 2014~ AS Physics

No, I got the same as you, and I know it's wrong. The graph was for the fixed resistor, not the LDR. I think we'll get 1/2 marks from that question.

Hehehe I'm gonna be here next year

do you all like the OCR B exam board?

what did you guys get for the ostrich question? how much smaller was the mass?

Question 9a (ii) is similar to the potential divider question in section A.

http://www.ocr.org.uk/Images/79820-question-paper-unit-g491-physics-in-action.pdf

It told you v of the LDR. R of the fixed resistor and vin

So 6-(Vldr)=Vfixedresistor this is then Vout.

So r2=6x800/2.5 -800 =1120 ohms



Check: V=IR. 2.5/800=I
So V= (2.5/800)/3.5=1120


Posted from TSR Mobile

V for fixed resistor (from the graph) is 3.8V.
We know that it's resistance is 800ohms.
6-3.8=2.2V for the LDR.
2.2= R for LDR/(800+ RLDR)x6
Rearranging and solving gives 463 ohms.

Graph?


Posted from TSR Mobile

V for fixed resistor (from the graph) is 3.8V.
We know that it's resistance is 800ohms.
6-3.8=2.2V for the LDR.
2.2= R for LDR/(800+ RLDR)x6
Rearranging and solving gives 463 ohms.

No need to worry. What is done is done.

I got 100% on all past papers and not a chance did I get 100% raw marks on that, I got at maximum about 55. This was an entirely new style of exam, with roughly 8 marks for not even physics answers. So what does this suggest?

Very low grade boundaries. It is not like June 2013 that was weird yet accessible, there were many questions which were just not accessible for the majority of candidates, especially the last two of section B. Therefore, an A will be in the region 32-40, without a doubt. It will not be above 40, there is no reason it can be. Therefore 100% will be at maximum 48, probably. Does anybody even know anybody that thinks they got 100% raw marks or did exceptionally well? I certainly don't.

How many marks do u think I'll lose for mixing up the resistance of the ldr and fixed resistor and getting like 1380 I think?

why is it not 1380?
3.8v=LDR volts
total V=6 therefore fixed must have 6-3.8=2.2v
fixed has resistance of 800-substitute this value into V=IR
2.2=Ix800
therefore I =2.2/800= 2.75x10^-3
then since current is constant substitute this value again into V=IR for the LDR
so 3.8=2.75x10^-3 R
Rearrange for R and you got 1380

By '100% will be at maximum 48' you mean that 48 marks would round to the full amount/100% of UMS?

No need to worry. What is done is done.

I got 100% on all past papers and not a chance did I get 100% raw marks on that, I got at maximum about 55. This was an entirely new style of exam, with roughly 8 marks for not even physics answers. So what does this suggest?

Very low grade boundaries. It is not like June 2013 that was weird yet accessible, there were many questions which were just not accessible for the majority of candidates, especially the last two of section B. Therefore, an A will be in the region 32-40, without a doubt. It will not be above 40, there is no reason it can be. Therefore 100% will be at maximum 48, probably. Does anybody even know anybody that thinks they got 100% raw marks or did exceptionally well? I certainly don't.

Yes I presume so. To work out 100% UMS, it is double the distance from a B to an A added onto the A. So for January 2010, it was 34 for an A and 29 for B, therefore 44 for 100UMS.

June 2009 36A, 31B, so 46 for 100% UMS.

Now, after having done all papers, both of those papers are a walk in the park in comparison. No stupid estimation questions or 'suggest a use of this' or 'why do they have the three squares' or that stupid show that question at the end. However, we must take into account that those papers were when the spec was new, so they had less practice, but they had plenty of legacy papers which are almost identical. So, I just don't see a high boundaries. I will discuss it with my teacher tomorrow.

Yes I presume so. To work out 100% UMS, it is double the distance from a B to an A added onto the A. So for January 2010, it was 34 for an A and 29 for B, therefore 44 for 100UMS.

June 2009 36A, 31B, so 46 for 100% UMS.

Now, after having done all papers, both of those papers are a walk in the park in comparison. No stupid estimation questions or 'suggest a use of this' or 'why do they have the three squares' or that stupid show that question at the end. However, we must take into account that those papers were when the spec was new, so they had less practice, but they had plenty of legacy papers which are almost identical. So, I just don't see a high boundaries. I will discuss it with my teacher tomorrow.

If I had perhaps 10-20 minutes more, I feel I could have logically worked through most of the 'hard' questions. Perhaps it was the exam pressure, especially the early hard questions which threw me, at home I've already figured out how to do the 'mass of graphene' question in a few minutes.

On past papers, I averaged around 51/60 (I completed 7). On this paper, I'll be lucky if I get an A.