# OCR Physics Unit 2 - G482 - (June Exams Preparation)Watch

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6 years ago
#921
(Original post by Gotzz)
Oh I see. I think I would've used 5.3x10^-7. I feel like it was 1060 though
You're right, I just made a mistake
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6 years ago
#922
(Original post by Gotzz)
Q1:
Define resistance. (1mark)
Calculate resistivity. (0.3Ωm). (3marks)
Using the I-V characteristics, explain why as temperature increases, the resistivity decreases. (4marks)
Q2.
Kirchhoff's 1st law and quantity conserved (2marks)
Kircchoff's 2nd law and quantity conserved (2marks)
Current in 750Ω resistor. (0.03-0.01=0.02A) (1mark)
V across 750Ω resistor. (15V)(1mark)
Resistance in two resistors.(1000Ω, 1500Ω) (2marks)

Random questions:
Define elecromotive force
Define the photoelectric effect
Define the electronvolt
Define progressive wave(2marks)
Differences between stationary wave and progressive wave (2marks)
Draw displacement-time graph (4marks)
Question 3 was potential divider question
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6 years ago
#923
(Original post by Georgehigginson)
chances are it'll be 150 ums, if not very close
Really? That low of a mark would get 150 ums?
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6 years ago
#924
(Original post by etmkndmpl)
Why it times 2? I thought is 3....
the order number N is two, because that is the second bright fringe
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6 years ago
#925
(Original post by blackstarz)
Really? That low of a mark would get 150 ums?
In physics, yes
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6 years ago
#926
(Original post by Titus20)
1060 was the correct answer in meters but they asked for the answer in nanometers, I made the same mistake. Drop one mark.
No, 1.06*10^-6 was the answer in meters.
if one wavelength was over a km long how the hell would it diffract through a slit smaller than a mm?
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6 years ago
#927
(Original post by Titus20)
1060 was the correct answer in meters but they asked for the answer in nanometers, I made the same mistake. Drop one mark.
1060 is in nm.
1.06 x 10^-6 is in m.
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6 years ago
#928
(Original post by Gotzz)
1060 is in nm.
1.06 x 10^-6 is in m.
You're correct, sorry. I gave my answer as 1.1x10^-6 (2sf), so I will drop a mark though.
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6 years ago
#929
(Original post by Gotzz)
In physics, yes
What mark are we talking about here sorry?
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6 years ago
#930
(Original post by Titus20)
What mark are we talking about here sorry?
80 something raw marks
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6 years ago
#931
(Original post by Gotzz)
80 something raw marks
Yeah, students seem to struggle a lot with physics, especially compared to chemistry, so it'll be low for full UMS
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6 years ago
#932
(Original post by OllieGCSEs)
Here is my reasoning with why R1 is 1000 and R2 is 1500:

We know that the p.d across R1 is 30V (45-15). So we know the expected p.d result (Vout) from a potential divider equation should be 30V.

The combination of the other two resistances in parallel will therefore need to make 500 when calculated, so that when you use the potential divider equation on R1, you get 30V, shown here:

Vout=R1/(R1+R2) *Vin

Note that R1 here does represent R1 in the circuit but R2 represents the resistance of the combo (R2 and the 750ohm Resistor)

So, we get: 30=1000/(1000+500) *45, which works.

Now that we know what the combination resistance needs to equal (500), we know that 1/500= 1/750 + 1/R2

Therefore 1/R2 = 1/1500 and R2 = 1500ohms

Does this clear things up for people? If there is another way to prove a different answer then please post it

Posted from TSR Mobile
You didn't even have to do that, I got to that with V=ir.
15/0.01= 1500 ohms
Then 30/0.03= 1000 ohms
I though well, it's only 2 marks it'll be simple, so I just used the theory of kirsch offs laws...

Posted from TSR Mobile
1
6 years ago
#933
(Original post by own)
You didn't even have to do that, I got to that with V=ir.
15/0.01= 1500 ohms
Then 30/0.03= 1000 ohms
I though well, it's only 2 marks it'll be simple, so I just used the theory of kirsch offs laws...

Posted from TSR Mobile
Yeah I think I did it that way too
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6 years ago
#934
(Original post by Titus20)
Yeah, students seem to struggle a lot with physics, especially compared to chemistry, so it'll be low for full UMS
I don't get that haha, I don't know if you do edexcel chemistry but its like 66/80 just for an a, hopefully this physics will be quite low, I found it tricky, spent too much time on bio and chem this week :/ I would say it is similar to the jan '13 paper if not trickier in some places.

Posted from TSR Mobile
0
6 years ago
#935
(Original post by Titus20)
Yeah, students seem to struggle a lot with physics, especially compared to chemistry, so it'll be low for full UMS
I'm quite the opposite
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6 years ago
#936
(Original post by theslav)
the order number N is two, because that is the second bright fringe

I did not know why I put 3 instead of 2... How silly me!! Do you think I can still get one mark for that?
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6 years ago
#937
(Original post by Gotzz)
Yeah I think I did it that way too
What did you get for potential difference of the 750ohm resistor as light intensity increases? I said as light intensity increases, resistance of LDR decreases. V=IR so V is directly proportional to R so decrease in p.d. P.d of LDR is same as p.d of fixed resistor also decreases.
0
6 years ago
#938
(Original post by own)
I don't get that haha, I don't know if you do edexcel chemistry but its like 66/80 just for an a, hopefully this physics will be quite low, I found it tricky, spent too much time on bio and chem this week :/ I would say it is similar to the jan '13 paper if not trickier in some places.

Posted from TSR Mobile
I'm with OCR and for unit 2 in chemistry 150UMS is usually about 97/100 raw, for physics unit 2 150UMS is usually about 85/100 raw..
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6 years ago
#939
(Original post by etmkndmpl)
I did not know why I put 3 instead of 2... How silly me!! Do you think I can still get one mark for that?
Possibly, but not sure, perhaps one for the method.
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6 years ago
#940
(Original post by Titus20)
What did you get for potential difference of the 750ohm resistor as light intensity increases? I said as light intensity increases, resistance of LDR decreases. V=IR so V is directly proportional to R so decrease in p.d. P.d of LDR is same as p.d of fixed resistor also decreases.
I can't remember now
0
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