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# AQA Physics PHYA1 - 24 May 2016 - RESIT [Exam Discussion Thread]

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1. (Original post by ShenanigansTVLV)
Yeah, so since it's AC then the total power would be equal to the peak voltage^2/resistance. Therefore, 325^2/12 = 8800W?
The heater is at its working power. Working power doesn't equal max power?
2. (Original post by 12ST)
is that the exam paper?
Nah, this question is from the past papers..not sure which one though..
3. (Original post by tort 779)
The heater is at its working power. Working power doesn't equal max power?
But this is before we assume any extra resistance and if the Vrms value is 230V then the actual value of the PD causing the heating effect would be the 325V anyway? Using the rms value calculates the average power but that isn't the same as the working power is it? I'm sure it's not because it specifies average power for the second power question but doesn't for the first?
4. (Original post by tort 779)
The heater is at its working power. Working power doesn't equal max power?
Is the working power not just the total power supplied by the heater when it is at a certain PD? So it would still be total and not average power unless it specified?
5. I didn't realise this thread was here and posted my post-exam writeup in the new spec thread. I'll put it here anyway.

1:
What is an isotope (2) variant of a molecule with same no. protons different no. neutrons

Find the number of electrons (2) should be 3, as the new charge was +4.8e

Fill in the blanks for uranium decaying into neptunium (3) +1 onto proton no., keep mass no. the same, should be a beta-minus with 0 mass no., and -1 proton no., and an anti-electron neutrino. (Mass number is the number which is lower down, and proton number the one higher up).

Fairly simple

2.
What is the process of an electron-positron pair being formed (1) pair production

Which quark structure shows a positive kaon (1) should be up, antistrange

Show that lepton number is conserved (2) it's zero before, the muon+ is an antilepton and neutrino is a lepton so 0 after too

What isn't conserved in the above interaction (K+ -> muon+ + neutrino) (1) strangeness

Fill in the table for a Positive Kaon, Positive Muon and a Neutrino, under the headings of Hadron, Meson, Charged, Baryon, Lepton (3)

A positive kaon can also decay into a positive pion and mystery particle X, identify X (3) I think it had to be a non-lepton, non-baryon, uncharged particle so must be a meson, I think I put neutral kaon or maybe a neutral pion

3.

How does excitation occur (3) collision of electrons accelerated by p.d. within tube collides with orbital electrons of the mercury move up a discrete energy level and some other stuff i don't fully recall

How does excitation cause photoelectric emission in the UV spectrum or something like that(2)

How is visible light formed (2) powder or paint coating on inner walls of tube has different energy levels for it's electrons who are excited by the other photoelectrons which have the exact energy required to excite them to a specific energy level and leads to different photoelectrons emitted or whatever

Find the characteristic frequency and state a unit for photons with energy of 1MeV, got something x10^20 but this is easily checkable (2)

Maybe another part after this, I don't remember

5.

Draw a labelled circuit that would allow the student to do the test with the diode (3) I did a cell with a variable resistor as a potential divider in series with a voltmeter/fwd-bias diode (which are in parallel), and an ammeter in series

6 marker, how to do the test between OA (from I/V graph in stem of question, which was from 0.6v up assuming that's the correct point) Things it said to do were why a datalogger would be advantageous, safety precautions for the experiment, how many results and the interval, as well as how the data would be gathered

6. over question

Find either the peak-peak voltage or peak voltage for a 230V 12W power supply (my friends differ on this) (2?) It was either 230sqrt2 to get 325v or 650v to get the peak to peak

Find the heating effect (3) Did P = I x I x R, for R = 18 Ohms, P / V = I = 115/6, then multiply the current by either the peak voltage or rms voltage, to get 6200W or 4400W

Wires have resistance of 0.0150 Ohms every metre, 2 wires each of length 3.15m, why will the oven not reach the desired voltage of 230V (2)

Find the voltage reached by the heating element due to the wires (3) I think it was 228V

Something else about heating effect due to resistance of wires, (1-2?) Got 34W

6. AC

What electrical element is shown by the the jump from P -> R (1) electromotive force I put

Find the value of this electrical element (1) They snuck in the scale of 2v/division so it should've been 6v if I remember correctly

Why does the line fall to PQ when the second switch is closed (2) There was the 18 Ohm resistor so it receives a portion of the p.d. or whatever

What is the current in the circuit when both switches are closed (2) I think it was 0.272727... = 0.27A = 5/18

Find the internal resistance of the battery (2 or 3) I got 21.6Ohms ON SECOND THOUGHTS maybe I put 21/6 to get around 3.5Ohms or something

updating as I remember more
6. (Original post by a.r.29)
I didn't realise this thread was here and posted my post-exam writeup in the new spec thread. I'll put it here anyway.

1:
What is an isotope (2) variant of a molecule with same no. protons different no. neutrons

Find the number of electrons (2) should be 3, as the new charge was +4.8e

Fill in the blanks for uranium decaying into neptunium (3) +1 onto proton no., keep mass no. the same, should be a beta-minus with 0 mass no., and -1 proton no., and an anti-electron neutrino. (Mass number is the number which is lower down, and proton number the one higher up).

Fairly simple

2.
What is the process of an electron-positron pair being formed (1) pair production

Which quark structure shows a positive kaon (1) should be up, antistrange

Show that lepton number is conserved (2) it's zero before, the muon+ is an antilepton and neutrino is a lepton so 0 after too

What isn't conserved in the above interaction (K+ -> muon+ + neutrino) (1) strangeness

Fill in the table for a Positive Kaon, Positive Muon and a Neutrino, under the headings of Hadron, Meson, Charged, Baryon, Lepton (3)

A positive kaon can also decay into a positive pion and mystery particle X, identify X (3) I think it had to be a non-lepton, non-baryon, uncharged particle so must be a meson, I think I put neutral kaon or maybe a neutral pion

3.

How does excitation occur (3) collision of electrons accelerated by p.d. within tube collides with orbital electrons of the mercury move up a discrete energy level and some other stuff i don't fully recall

How does excitation cause photoelectric emission in the UV spectrum or something like that(2)

How is visible light formed (2) powder or paint coating on inner walls of tube has different energy levels for it's electrons who are excited by the other photoelectrons which have the exact energy required to excite them to a specific energy level and leads to different photoelectrons emitted or whatever

Find the characteristic frequency and state a unit for photons with energy of 1MeV, got something x10^20 but this is easily checkable (2)

Maybe another part after this, I don't remember

5.

Draw a labelled circuit that would allow the student to do the test with the diode (3) I did a cell with a variable resistor as a potential divider in series with a voltmeter/fwd-bias diode (which are in parallel), and an ammeter in series

6 marker, how to do the test between OA (from I/V graph in stem of question, which was from 0.6v up assuming that's the correct point) Things it said to do were why a datalogger would be advantageous, safety precautions for the experiment, how many results and the interval, as well as how the data would be gathered

6. over question

Find either the peak-peak voltage or peak voltage for a 230V 12W power supply (my friends differ on this) (2?) It was either 230sqrt2 to get 325v or 650v to get the peak to peak

Find the heating effect (3) Did P = I x I x R, for R = 18 Ohms, P / V = I = 115/6, then multiply the current by either the peak voltage or rms voltage, to get 6200W or 4400W

Wires have resistance of 0.0150 Ohms every metre, 2 wires each of length 3.15m, why will the oven not reach the desired voltage of 230V (2)

Find the voltage reached by the heating element due to the wires (3) I think it was 228V

Something else about heating effect due to resistance of wires, (1-2?) Got 34W

6. AC

What electrical element is shown by the the jump from P -> R (1) electromotive force I put

Find the value of this electrical element (1) They snuck in the scale of 2v/division so it should've been 6v if I remember correctly

Why does the line fall to PQ when the second switch is closed (2) There was the 18 Ohm resistor so it receives a portion of the p.d. or whatever

What is the current in the circuit when both switches are closed (2) I think it was 0.272727... = 0.27A = 5/18

Find the internal resistance of the battery (2 or 3) I got 21.6Ohms ON SECOND THOUGHTS maybe I put 21/6 to get around 3.5Ohms or something

updating as I remember more

I said 3 for the electrons too as I thought it asked for the number of electrons removed to produce the ion but a lot of people are saying the number of electrons in the ion instead. Also, as it didn't specify average power for the first power question I got 8800W because I thought you had to use the actual peak value and only the rms value when it states average power?
7. (Original post by tort 779)
The heater is at its working power. Working power doesn't equal max power?
It is mean for AQA to make you work out the peak volatage and then make you use the rms in the next question but oh well, what's done is done.
8. (Original post by ShenanigansTVLV)
Is the working power not just the total power supplied by the heater when it is at a certain PD? So it would still be total and not average power unless it specified?
This is all i can find on AC circuits and it says that to apply P=V^2/R you need to use Vrms:
http://www.s-cool.co.uk/a-level/phys...and-rms-values
9. (Original post by tort 779)
This is all i can find on AC circuits and it says that to apply P=V^2/R you need to use Vrms:
http://www.s-cool.co.uk/a-level/phys...and-rms-values
My AQA textbook says that V^2/R = Power of an AC supply and that Vrms^2/R is only used to calculate mean/average power supplied by AC Current>
10. I went with particle X as being a pi 0? Had to be neutral, not a lepton and not a baryon?
11. (Original post by Brettm98)
I went with particle X as being a pi 0? Had to be neutral, not a lepton and not a baryon?
Correct
12. (Original post by tort 779)
Photon is the exchange particle (boson) for electromag interaction. I believe its not a suitable answer because a boson of electromag interaction cant be created in a weak interaction.
You mean a virtual photon, that's not the same thing. Virtual photons cannot be detected. Either way, like I said, I don't think that a photon was a suitable answer for particle X. I said it was a pi^0 meson
13. (Original post by ShenanigansTVLV)
Realistically, a photon could be correct but AQA like to ask ambiguous questions with a variety of possible answers and then only give the marks for a specific one they choose.
I didn't say X was a photon, I said it was pi^0. I was just simply explaining that a photon is actually a particle. If it weren't, the photoelectric effect (amongst other things) wouldn't exist lol
14. (Original post by Brettm98)
I went with particle X as being a pi 0? Had to be neutral, not a lepton and not a baryon?
Yup
15. I think people are exaggerating how easy it was.
People that weren't revising to get A's (which realistically makes up most of the people who took the exam) will have probably messed up the diode and heater questions, since the diode questions were a fairly small part of the syllabus, and the heater question was a pain.
I'm going with 53-55 for an A.
16. For the six marker, what are the safety precautions of a diode in a circuit??
17. (Original post by Normal.Person)
For the six marker, what are the safety precautions of a diode in a circuit??
I wasnt sure on that myself i just put to wear some gloves to insulate hands and avoid water
18. Personally paper wasnt much different from recent years however was worded different which mad it harder. Id say 54 for A
19. (Original post by Boro12345)
I wasnt sure on that myself i just put to wear some gloves to insulate hands and avoid water
Loool I got bored so I started writing "though there are no reports of people dying from diodes, safety precautions are recommended"
20. (Original post by Boro12345)
I wasnt sure on that myself i just put to wear some gloves to insulate hands and avoid water
ensure diode is in correct direction in circuit

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