AQA AS Physics A Unit 1 January 2012 Discussion

A remember when I sat a unit 1 paper and a question came up asking to graph the characteristic graph for a semi-conductor and 0.6 v had to be shown but they accepted a range at which the gradient started to increase.

0.6v isn't a particularly tough figure to remember and it's defo worth doing a lot of questions on voltage characteristic graphs and learning their properties and key values.

LHS
BN=
K(-) has baryon number of -1/3
p has BN of 1
Q=0
S=1




RHS=
S=2
Q=1
X must have S=-1 Q=-1 BN=2/3
Therefore a sigma minus baryon is needed.
with Q=-1 S=-1 BN=2/3
has quark structure dds

I agree. Are they hard to remember. I just find all the graphs really long

Classification of particles
Hadrons: baryons (proton, neutron) and antibaryons (antiproton and antineutron) and mesons (pion, kaon).
Hadrons are subject to the strong nuclear force.
Candidates should know that the proton is the only stable baryon into which other baryons eventually decay; in particular, the decay of the neutron should be known.
Leptons: electron, muon, neutrino (electron and muon types).
Leptons are subject to the weak interaction.
Candidates will be expected to know baryon numbers for the hadrons. Lepton numbers for the leptons will be given in the data booklet.
07)
Quarks and antiquarks
Up (u), down (d) and (s) quarks only.
Properties of quarks: charge, baryon number and strangeness.
Combinations of quarks and antiquarks required for baryons (proton and neutron
only), antibaryons (antiproton and antineutron only) and mesons (pion and kaon)
only.
Change of quark character in β- and β+ decay.
Application of the conservation laws for charge, baryon number, lepton number and strangeness to particle interactions. The necessary data will be provided in questions for particles outside those specified.

when calculating specific charge, do you use atomic units mass from the data sheet, or do you use separate proton and neutron masses?

doesn't make much difference but may mean getting a question wrong by a small amount

1. Voltage Rules for Series and Parallel
2. Same for Current and Resistance as above
3. Experiments (6 markers) for Thermistors/Resistance etc
4. Internal resistance and the graph
5. Oscilloscope rules
6. Car motors
7. Charge, Power (which is the same as energy dissapted)

Umm what about car motors i don't think i've done anything about that

Its just like, why won't a car start if the battery has a high internal resistance, and you have to be all, there wont be enough charge to get the car started etc

Please help. The event represented by, K(-) + p → K(0)+ K(+) + X, is a strong interaction. The question is what will particle x decay into? If you know please explain why?

It's mostly just in how you apply internal resistance to other situations, really.


The question here really is "what is X"? Given that baryon number is always conserved, X must be a baryon (as there is one baryon on the left-hand-side). The only stable baryon is a proton; thus, the baryon would have to decay into a proton and then be unable to decay further.

Someone correct me if I'm talking rubbish, this seems about right to me.

And for the mass (assuming its a nucleus) you add the proton mass and the neutron mass.
I was wondering which value you use on the data sheet
Atomic mass unit, or separate proton and neutron masses.
I think it is the later but I'm not shure.

And for the mass (assuming its a nucleus) you add the proton mass and the neutron mass.
I was wondering which value you use on the data sheet
Atomic mass unit, or separate proton and neutron masses.
I think it is the later but I'm not shure.

It's mostly just in how you apply internal resistance to other situations, really.


The question here really is "what is X"? Given that baryon number is always conserved, X must be a baryon (as there is one baryon on the left-hand-side). The only stable baryon is a proton; thus, the baryon would have to decay into a proton and then be unable to decay further.

Someone correct me if I'm talking rubbish, this seems about right to me.

You need to use SI units so mass in kg and Q in C rather than mass in u because specific charge (charge/mass ratio) is given in the units C/kg

The value on the data sheet gives the mas of one u in kg meaning the value is the same for protons and nutrons, however you could also us the separate masses given, giving a slightly different result.

I will check a mark scheme at some point if I can find one

Yes , also this decay is a weak interaction so strangeness doesn't have to be conserved. Unlike the original interaction which was a strong interaction.

Is anyone doing the ISA unit on resistance?