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OCR Physics B G491 20th May 2013

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if the incoming curvture is -0.4, and the power of the lens is 5D, then that would mean that the new curvature is 4.6D, right? :s-smilie:

Reply 81

zcQ

Original post by HayyanN

I got 30 for the conductance. I think the other was in series was 20 s. so I did 1/20 + 30 + 30 which rounded to 30. Is that wrong?

I got 15 because the two in parrallel were 15 each so 15+15=30 and the other one was 30 on series so 1/30 +1/30 gives 2/30. Inverse = 15

Reply 82

Hicko

I got a power of 4.6 aswell : )

Reply 83

SlayerOfTheHero

I thought most of the paper was fine really, the last section on materials being quite tricky considering it was materials which I thought most people deemed perhaps the easier part of the course. The last few questions were very challenging in my opinion and managed only to scribble some working.

What do reckon as grades for an A guys?

Reply 84

eversonlloyd6

Original post by Hicko

I got a power of 4.6 aswell : )

HICKO, if you are/were a girl, I would marry you xD Let's hope it's right xD

Reply 85

eversonlloyd6

P.s. I'm on a friend's account, my account name is: "jelmes96"

Reply 86

Josh-B

Original post by eversonlloyd6

HICKO, if you are/were a girl, I would marry you xD Let's hope it's right xD

I got this also, don't need a marriage proposal though!

Reply 87

jelmes96

haha.... Well I was so unsure about this paper. The maths questions were so obscure, and I would personally say I'm a really good mathematician (for my age that is)....so yeah...I found the writing questions easy. I missed 3 marks. The very last mark, and the 2 other pieces of information from the heart sensor graph. I was like, WTF

I also got 4.6D

Yeah saying that, the heart rate monitor one threw me off a bit. What did people say for the other features the figure gave?

Reply 90

jelmes96

Didn't put anything...only 2 marks :biggrin:

Reply 91

Salamanderf

Original post by SlayerOfTheHero

A-43
B-38
C-35
Thought the paper was decent :smile:

Reply 92

King Hotpie

Very strange paper I thought... Nothing like any of the past ones. Hoping that will lower grade boundaries a bit.

Reply 93

Fordey

I really do think that us year 12's are the trial year for OCR
They kind of put all new stuff in the exam which no one has a clue about

Reply 94

HayyanN

What did people put for the why concrete is good under compression and bad in tension. I drew a structure of two different sized atoms bonded together in a random structure. Then I said that when under ension, there is a high concentration for the stress at the tip. The irregularly structure does not allow for slips and hence this results in brittle pcrack propogation through the material. However, the bonds themselves are extremely strong and hence is effective under compression. In hindsight, could have answered it a lot better than this :/

Reply 95

jelmes96

Uh...dropped a mark on the first part.... uh LED and lightbulb graph the wrong way round...FML

Reply 96

jelmes96

Can someone please upload the paper?

Reply 97

metaltron

Really rough unofficial mark scheme, will be added to when people start commenting.

1. D (Diode) F (Fixed Resistor) L (Filament Lamp) (3)

2a) Difficult to scratch or dent (1)
b) Axe head would become blunt if soft (1)
c) Tough (1) so axe head does not shatter if a crack forms
OR Strong (1) so axe head can withstand large forces (1)

3a)

2 \times 10^{-5} s

160-20 = 140kHz

1000

4a) Current = VG (can't remember values)
b)

15mS

5a) 5D
b) 4.6 D

6a) 10730J (Is 3sf OK, I settled for 3sf in the end)
b) Energy / 540s = 20W (to 2sf) / 19.9 W (to 3sf)

7. no.of levels = 200/0.5 + 1 = 401
so no. of bits = 9

8a) i) Directly proportional to each other
a)ii) Sensitivity = 1.5
b) 72 bmp
roughly 113 pressure units
c) Heart beats last for same time
Peak pressure heart beats falls then rises then falls...

9a)i) 0.857 Mbyte < 1Mbyte
ii) Estimate and then execution.
b) i)

1.14 \times 10^5 bits^{-1}

ii) Yes because frequency is higher than the information transfer rate.
iii) Stops deforestation linked to climate change/ etc. (1)
Puts people out of jobs/ too expensive for some people to buy appropriate technology/ etc...

10a) i) Concrete made of stones/ aggregate and cement, which both contribute their properties to the material.
ii) Any four from these and possibly more:
Stones are stronger than cement (1)
Weakest point is at boundary between stones and cement (1)
Under compression, the stress is concentrated on the stone (1)
Under tension, the stress is concentrated on the cement (1)
Brittle fracture occurs sooner in the cement that the stones (1)
b) i) 5
ii) 3
c) i) Stress = F / CSA (1), same force but 5 times CSA leads to 1/5 stress (possibly shown through algebra) (2)
ii)

1.5 \times 10^8 Pa

Reply 98

King Hotpie

What did people get for the 'estimate the factor that the intensity has increased' or something like that, the logarithmic scale thing for the dolphin click question. I put 10^7, then crossed it out and changed to 10^6.7 :s-smilie:

Reply 99

Dan1300

i put 10^7