# AQA Physics Unit 1 PHYA1 20th May 2014 OFFICIALWatch

4 years ago
#341
if you put weak with W^+/- is that wrong?
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4 years ago
#342
Okay then Einstein, what did you do for the last question? Did you use the set up they provided or did you add an ammeter, waterbath, thermometer whatever and then start your calculations and assumed measurements?

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4 years ago
#343
I feel like crying. Reading other people's answers is making me realise how much I got wrong. I really want an A
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4 years ago
#344
I think there are some questions missing and am unsure about the resistance of the tin for the resistivity one.

AS Physics Unit 1 Mark Scheme

1a)K+=US bar(sorry can’t do bar symbol) because strangeness=1 therefore anti strange quark and charge is 1 so up’s charge of 2/3 is required to add with 1/3 charge of anti-strange to make 1 full charge.(not required) (1)
1b)Baryon Number=0 because it’s not a baryon or baryon number=1/3-1/3=0(not required) (1)
1c)K- because charge is opposite for antiparticle(not required).(1)
1d)beta minus decay electron/beta minus 0 -1 and antineutrino and 26,7 I think either way it was the element given plus 1 on the proton number and the same neutron number.
1e)K- to anti muon + muon neutrino
K- is a hadron,meson and is charged.
Anti muon is charged, isn’t a meson or hadron.
Muon Neutrino isn’t charged, isn’t a meson or a hadron.(3)
1f)Particle X is a neutral pion so that baryon number,lepton number and charge are conserved(not required).(1)
1g)Either baryon number, charge or lepton number conserved.(1)
2a)Q has the least protons(5) compared to 6,6 and 8.(1)
2b)P and R are isotopes due to having same number of protons.(2)
2c)atom with lowest proportion of charged particles(protons) to mass(protons and neutrons)(nucleon number).P I think can’t remember.(6 protons,14 nucleons) (2)
2d)strong nuclear force is repulsive up to 0.5-1.0 femtometres then it becomes an attractive force decreasing with distance separated between proton and neutron up to 0 at the range of strong nuclear force(3-4 femtometres).Graph would be good idea straight line down at 0.5-1.0 from repulsion to attraction and then it curves up to 3-4fm.(3)
2e) Weak Interaction exchange particle(Weak Boson W+ or W- or Z0) {EDIT:Looks like it is the Electromagnetic Force with exchange particle Virtual Photon I'm not sure of the question though that would help)(2)
3a) Interference with Double Slits has been observed with electrons.(1)
3b) wavelength=h/mv=6.63*10^-34/(9.11*10^-31*2.5*10^5)=2.9*10^-9 m(2sf)(3)
3c) velocity=h/(wavelength*mass)=1.2*10^3 ms^-1 (2)
3d) C=fwavelength frequency=3*10^8/(254*10^-9)=1.2*10^15 Hz(2)
3e) E=hf=6.63*10^-34*1.2*10^15=7.9*10^-19J =7.8*10^-19j=7.8*10^-19/(1.6*10^-19)ev=4.9ev(2)
4a)Ultraviolet Photons are emitted by mercury atoms(1).
4b) excited is where electrons in the mercury atom receive enough energy to move up energy levels.(2)
4c)electrons flow from either end of metal plates and collide with mercury atoms transferring their energy givi ng electrons enough energy to move to the next energy level.(2)
4d)The Excited electrons can then lose a varying amount of energy and drop different amounts of energy levels as they dexcite and because the difference between energy levels refers to the energy of the photomn released then different energy photons can be released and because photon energy is dependent on its frequency e=hf then differing frequencies can be produced.(3)
4e) Ultraviolet photons are incident on the fluorescent tube exciting the electrons in the flourscent tube as they receive enough energy to move to the next energy level and then they lose energy dropping energy levels as the dexcite and the difference between energy levels is the energy of visible light so visible light is emitted(2)
5a)Resistivity is the constant of proportionality of the directly proportional relationship of resistance and the ratio of length and cross sectional area for a specific material providing temperature remains constant.Resitivity is the product of resistance and the ratio of cross sectional area and length.(2)
5b)The Critical Temperature is the temperature at which below this a material becomes a superconductor and has zero resistance and it is significant because of this and that a material with a higher critical temeperature would be more useful.(2)
5c) P=RA/L=0.80*(0.5*10^-3)^2*pi/4.8=1.3*10^-7ohmmetre(unit required)-I’m not sure if it was 0.80 ohm resistance though.(2)
6a)The power is directly proportional at first(straight line) increasing as resistance increasing between 0.5-3 ohm up to a maximum of 3.0 watts but after this it has an inversely proportional relationship decreasing as resistance increases.(use figures)(2)
6b) at resistance 0.8 ohm power=1.9 p=i^2 sqrt(p/r)=i=sqrt(1.9/0.8)=1.5 amps (2)
Current=1.5 amps
6c) voltage=1.2 volts v=ir=1.5*0.8=1.2 volts (2)
6d) internal resistance=3.2 ohm emf=v+Ir (emf-v)/I=r=(6-1.2)/1.5=3.2 ohm (2)
6e) without internal resistance then the terminal voltage=emf and thus the equation P=V^2/R would work for the whole circuit therefore power would have an inverse relationship with resistance decreasing as resistance increased.(2)

7a) you would measure voltage/pd with a voltmeter and temperature with a thermometer. Heat thermistor with water bath(7 different readings between 0 and 100).R is required because otherwise voltmeter reading would equal emf and not change due to r as temperature increases and the resistance of the thermistor drops it will receive less potential difference due to having a resistance lower in proportion to R therefore the voltmeter reading will drop.Set up the experiment again and measure the potential difference across thermistor in room and compare with graph(I drew curved falling curve of voltmeter reading against temperature and indicated lines drawn to find out the temperature if you know the voltmeter reading.(6)
7b) If the voltmeter is connected across R then as the resistance of the thermistor decreases due to temperature increasing its resistance will be greater in proportion to the resistance of the thermistor so the reading on the voltmeter would increase.(3)

I think the paper was generally easy and whether or not some of us may have misread a question and put weak instead of electromagnetic it was a nice paper a decent bit harder than last year though so I would say A-54 B-47 C-39 D-32 E-26 with 100% UMS at 68/70
2
4 years ago
#345
Ohh noo, I wrote electroSTATIC force with a photon for the exchange particle. Would I still get the marks?
0
4 years ago
#346
what were the total marks for electricoty question?
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4 years ago
#347
(Original post by ChordaeTendineae)
no lost volts, terminal pd=emf and i said there less resistance so current increases, so using P=IV power increases and i linked it to the graph
I put that the overall power dissipated would be greater yeah because current is greater and voltage is greater across the resistor but I also wrote about how as the restance increases, the power would decrease because the total current in the circuit would decrease yet the voltage across the resistor would stay the same? is that what the question was getting at?
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4 years ago
#348
Not so "thesmartone" after all then eh?

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4 years ago
#349
Please tell me the answer for that question on electrons having a wave-like nature was 'diffraction'. PLEASE.
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4 years ago
#350
No oscilloscope questions ia ssumed there would be some because our isas wwre based on resisitivity
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4 years ago
#351
(Original post by LxH)
For interaction between protons I said repulsion, virtual photons
For particle produce in the decay I said neutrino (conserves charge and number of mesons)
Got 17 Ohms for internal resistance
Missed out question on speed of muons
What the **** happened to me in that exam? I'm ****ing ruined. No way I'm getting into Leeds now having handed in this absolute **** stain of a paper. I can ****ing forget chemical engineering. A resit is not optional. I got a C in the ****ing ISA aswell. I can't scrape this back with mechanics either. Highest I'll get this year is a B and that's insufficient as ****.
I got 5 AAA offers from Leeds, UCL, etc etc for Chemeng with BBBD at AS. Chill your beans, you'll be fine.
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4 years ago
#352
Not so "thesmartone" after all then eh?

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Haha! I arrogantly chose that username during GCSE's when I was getting As and A*s. Wish I could change it now trust me.
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4 years ago
#353
In question 2 which nuclei had the lowest specific charge and why?
Also I can't remember which question but explain the shape of the graph between 0.5-6.5 ohms?
0
4 years ago
#354
(Original post by TheSmartOne)
Please tell me the answer for that question on electrons having a wave-like nature was 'diffraction'. PLEASE.
it was definitely diffraction
1
4 years ago
#355
(Original post by TheSmartOne)
Please tell me the answer for that question on electrons having a wave-like nature was 'diffraction'. PLEASE.
The answer is 'Electron diffraction'. Would guess you get the mark for saying diffraction.
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4 years ago
#356
(Original post by LxH)
it was definitely diffraction
Diffraction is a possibility but the interference pattern from the double slit experiment should get you the mark.
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4 years ago
#357
(Original post by chiaretta)
I put that the overall power dissipated would be greater yeah because current is greater and voltage is greater across the resistor but I also wrote about how as the restance increases, the power would decrease because the total current in the circuit would decrease yet the voltage across the resistor would stay the same? is that what the question was getting at?
That's what I was going to write! But I had used up all the lines so I thought that I might have written enough...
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4 years ago
#358
(Original post by simon105)
I got 5 AAA offers from Leeds, UCL, etc etc for Chemeng with BBBD at AS. Chill your beans, you'll be fine.
oh my god. i was told i needed at least three As at AS to get into leeds! thank you so much you genuinely just made my day
0
4 years ago
#359
whats been the highest ever raw mark for an A?
0
4 years ago
#360
(Original post by mathmo1)
In question 2 which nuclei had the lowest specific charge and why?
Also I can't remember which question but explain the shape of the graph between 0.5-6.5 ohms?
I worked them out for question 2 because couldn't see an obvious way of telling. I think it was the 3rd one down in the table, with 14 nucleon number but I did it quickly so I'm not sure. For the explanation I put the specific charge formula and explained that a lower charge divided by a higher mass will give a small value. Don't think I got the 2nd explanation mark though.
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