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# AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread] watch

1. (Original post by PhyM23)
I think it's 1/4 since that's the distance from an antinode to a node
although its not?
2. (Original post by -jordan-)
This is what I thought too.

This is 1/4 of a wavelength:
Attachment 557587

This is 1/2 a wavelength:
Attachment 557587557589
Do you rmemeber what the question was asking?
3. (Original post by SirRaza97)
Do you rmemeber what the question was asking?
Minimum distance the reflector could be moved in order to go from maximum detection of the waves to minimum. So constructive interference to destructive.
4. Is there an unofficial mark scheme or anything yet? I'd like to confirm that I've probably got a D oops
6. (Original post by -jordan-)
This is what I thought too.

This is 1/4 of a wavelength:
Attachment 557587

This is 1/2 a wavelength:
Attachment 557587557589

I did divide by a half but it's definitely divide by a quater.

Half gives you the distance between 2 nodes.
But

Node = minimum strength.

Antinode= maximum strength.

So to get the distance between minimum and maximum strengths, divide by a quater
7. (Original post by perpetua)
Applied physics anyone? What did u get for the efficiency
34.5%

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8. (Original post by -jordan-)

1)
a) Cathode rays are electrons, specific charge was 1800x that of a H+ ion, so mass is very light.
b) Electron beam collides with the gas atoms, causes ionisation, the gas gets excited and then de-excites, emiting photos in the visible light spectrum.
c) 9.1x10^10 for the calculated specific charge.
2
a) 6 marker. Increasing potential difference increases work that needs to be done against the potential difference for electrons to move across the gap, as you increase the potential difference the current will increase. Therefore the kinetic energy of the electrons will be reduced. At the point where current is zero is the stopping potential. Can be used to find the maximum kinetic energy by calculating eV. Einstein's equation is hf = thi + ekmax where ekmax can be replaced by eV and used to find the work function or the frequency.
b) Work function - can't remember.
c) Can't remember what I got here either - 21 or 25?

3)
a Electric field and magnetic field, 180 degrees in phase
b) Increasing the distance means that it reflects back at a different point in the wave cycle, so a different number of wavelengths is reflected back, the phase difference is different and therefore they destructively interfere rather than constructively interfere
c) Should be 0.034m
d) Speed of light is 3x10^8 - I was unsure about this one. Did anyone think it was a poorly worded question? What did they mean by the ORIGINAL assumption that light was electromagnetic? Did that mean the assumption before this experiment, or the very first instance?

4) a) Show that question.
b) Something very small, show that answer from part a * distance * 1000
Probably should add the fact that 3b was largely about the fact that stationery waves are formed
9. How many marks was the intensity question worth (Q2), and the cylinder of air one (Q3)? And what was the other question, Q1 was radius and Q5. was heat capacity?

How many marks was Q2 worth for TP and Q3? The ones with the stopping potential and electromagnetic waves

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10. (Original post by Mango Milkshake)
for the first question, did you use the angle as 42.5? in sintheta
yeah. I'm sure they'll probably take anything between 40 and 45.
yeah. I'm sure they'll probably take anything between 40 and 45.
Do you remember how many marks was Q1 worth?

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12. (Original post by Yo12345)
Do you remember how many marks was Q1 worth?

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I don't think that was Q1 but Q1 was worth 10 marks if I remember correctly. Why?
13. Last question: what was the question for the fission and fusion following the first one about why either are on either side of the graph, the one before working out the mass difference?

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14. (Original post by Yo12345)
Last question: what was the question for the fission and fusion following the first one about why either are on either side of the graph, the one before working out the mass difference?

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The question about why fusion released more energy than fission?
15. I missed all the stuff but nobody seems to do applied here wtf lol
I can't remember any of my answers. I was so desperate to get out of the exam my mind was somewhere else lmao. Prob lost marks for Boyle's law assumption, adding bg radiation back, six marker as always, and some picky ass MS for the fusion/fission business, and a couple on applied due to six mark, but who cares, WE ARE DONE WITH A LEVELS
16. (Original post by SirRaza97)
The question about why fusion released more energy than fission?
That was part a, I think. There was one after that and before the Q about mass defect

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17. (Original post by Yo12345)
That was part a, I think. There was one after that and before the Q about mass defect

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The questions were from what I can remember in no order:

- Why fission and fusion is restricted to parts of the graph?
- Why fusion releases more energy?
- Mass defect of oxygen?
- The energy released when oxygen forms?
- How can you use the graph to calculate the binding energy of oxygen?
18. (Original post by C0balt)
I missed all the stuff but nobody seems to do applied here wtf lol
I can't remember any of my answers. I was so desperate to get out of the exam my mind was somewhere else lmao. Prob lost marks for Boyle's law assumption, adding bg radiation back, six marker as always, and some picky ass MS for the fusion/fission business, and a couple on applied due to six mark, but who cares, WE ARE DONE WITH A LEVELS
Applied over here

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19. (Original post by SirRaza97)
The questions were from what I can remember in no order:

- Why fission and fusion is restricted to parts of the graph?
- Why fusion releases more energy?
- Mass defect of oxygen?
- The energy released when oxygen forms?
- How can you use the graph to calculate the binding energy of oxygen?
I think your first 2 questions were 1 question?

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20. (Original post by Yo12345)
I think your first 2 questions were 1 question?

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No they weren't they were seperate questions each 3 marks I think. It would be a lot to ask that in one question.

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