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# OCR Physics A Exam - G482 Electrons, Waves, Photons [09/06/16] watch

1. (Original post by Reda2)
I did V = E - Ir
so V = I (-r) + E

Plotted the graph V against I, gradient equal to -r.
i just stated all of that rather than actually drawing a graph to illustrate that, thats calm right?
2. (Original post by Artmanlikesart)
That's what I did too, what did you put for the reason for the second resistor?
I didn't know the answer to that one so just wrote something random. I said so there is always a resistance with the internal resistance when the variable resistor is 0.. wrong most probably but might get me 1 mark. What did you say?

And for the difference between something about waves, if you remember what question, what did you write?
3. (Original post by Hasib98)
i just stated all of that rather than actually drawing a graph to illustrate that, thats calm right?
calm?

They did give you empty space so I think they were expecting you to draw the graph. Maybe you will lose 1 mark for that.
4. I'll post one tomorrow - I wont be able to get hold of a copy of the paper until then.
5. (Original post by Reda2)
I didn't know the answer to that one so just wrote something random. I said so there is always a resistance with the internal resistance when the variable resistor is 0.. wrong most probably but might get me 1 mark. What did you say?

And for the difference between something about waves, if you remember what question, what did you write?
I said that if the variable resistor was at 0 ohms then huge current could damage the components or blow the circuit entirely.
Difference of waves? What do you mean?
6. sorry to be that guy, but i thought it was a really simple paper even though it was a bit non standard
7. (Original post by Reda2)
calm?

They did give you empty space so I think they were expecting you to draw the graph. Maybe you will lose 1 mark for that.
Buuut it didnt say draw a graph stupid questions
8. (Original post by Artmanlikesart)
I said that if the variable resistor was at 0 ohms then huge current could damage the components or blow the circuit entirely.
Difference of waves? What do you mean?
I can see your answer in the marks scheme. I don't remember but in one of the waves question there was a comparison question or advantage vs disadvantage question.
9. (Original post by Reda2)
I can see your answer in the marks scheme. I don't remember but in one of the waves question there was a comparison question or advantage vs disadvantage question.
Where's the markscheme?
Do you mean the difference in powers of ten between waves?
10. (Original post by Tyler'sD)
sorry to be that guy, but i thought it was a really simple paper even though it was a bit non standard
I agree, but that stationary waves question was no where near simple. That is the question that got me. The rest was all do-able. Calculations were really easy, some of the explanations as well. But overall not bad. Definitively above 120 UMS for me.
11. (Original post by Artmanlikesart)
Where's the markscheme?
Do you mean the difference in powers of ten between waves?
hehe, no I meant your answer is something that I can imagine in the mark scheme, because it makes sense.

12. (Original post by Reda2)
I agree, but that stationary waves question was no where near simple. That is the question that got me. The rest was all do-able. Calculations were really easy, some of the explanations as well. But overall not bad. Definitively above 120 UMS for me.
What about it was unusual for you?
13. (Original post by Artmanlikesart)
That's what I did too, what did you put for the reason for the second resistor?
I said it was for safety reasons because if the variable resistor had a resistance of 0 and there was no fixed resistor, the current would be way too high (infinite?) and it would overheat.

Was a bit of a guess to be honest.
14. (Original post by Tyler'sD)
sorry to be that guy, but i thought it was a really simple paper even though it was a bit non standard
I thought it was fairly easy as well, especially compared to last years paper
15. (Original post by Tyler'sD)
What about it was unusual for you?
The stationary wave question, the tube stuff and all the drawing we had to do, and the 2-3 marker written part in the question. Really only that question, not seen like it in past papers. I lost 4 marks in the show velocity question where you had to use eV = 1/2 mv^2. What about you?
16. You are a dirty swamp goblin
17. (Original post by Reda2)
The stationary wave question, the tube stuff and all the drawing we had to do, and the 2-3 marker written part in the question. Really only that question, not seen like it in past papers. I lost 4 marks in the show velocity question where you had to use eV = 1/2 mv^2. What about you?
Good paper for me, the ones im not sure if i got was the why the 3ohm resistor and i dont know if i proved it was 30mA correctly in the LED, i worked out the LED resistance then worked out the voltage in the resistor then worked out the current, it that what everyone else did??
18. (Original post by NickLCFC)
I said it was for safety reasons because if the variable resistor had a resistance of 0 and there was no fixed resistor, the current would be way too high (infinite?) and it would overheat.

Was a bit of a guess to be honest.
With zero resistance in the circuit (except the internal reistance) it's the same as a short circuit, which needs to be prevented of course
19. and yeah last years paper was so dumb
20. At least overall it was an improvement from last years paper.
Two things I struggled with the most were the last two questions of the battery charging and internal resistance question, then the second half of the standing wave questions

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