(Original post by PhysicsGirl)
I can't remember too much either, especially not the correct question numbers but I think a few of the wordier section A questions answers were;
2) a) neutron
3. Was this the proton question? If so, field strength = 0 because field strength = force per unit charge, forces cancel therefore field strength = 0
and potential doubles because you've added another potential 'hill' on the other side
4) choosing the correct region of the graph? -A
5) number remaining in the decay question? As Oromis said, it was 55% :-)
And I think that's all I remember for section A
9) a) Question went something like this: Explain why the electron travels in a curved path. Mention the varying force; you may add arrows to the diagram if you want
. My answer: I annotated the diagram, said the force from the nucleus was negligible in the straight bits, and drew arrows on the curved bit perpendicular. Then wrote a waffly explanation using f=kqQ/r^2, talked about the force increasing as r decreased, mentioned parabolic nature of path. Probably not the most efficient way, but I went for trying to cover everything.
Was this the one with the graph on it and you had to use the n=1.2 for the minima, work out the de Broglie wavelength and then use that to calculate an energy? Or something like that?
10) This was the permeability question, I think? First wordy bit was talking about what would happen to the flux (I think it was flux?) when the core cracked and created an air gap (air = significantly lower permeance, therefore reduces the total permeance of circuit, therefore flux is reduced by the equation: flux= permeance * current-turns). Then asked to discuss whether the opinion that the permeability of iron had changed because the permeance of the circuit had fallen. (no- permeability of iron is fixed (material property), formula is still correct but the magnetic circuit is no longer made entirely from iron, therefore permeance no longer follows that relationship)
11) This might have been the proton beam question. Work out a risk, then the state and explain for what penetration the proton beam was most effective, then use the graph to explain why the number gained in part b) was a minimum.
12) This was the grain between the vertical plates question, I think. You had to draw five field lines (I went for five, horizontal, parallel, equally spaced, lines running from positive to negative but I'm not entirely sure they had to be equally spaced?) and then a 24kV equipotential line (vertical line down centre, perpendicular to field lines) and then the other wordy bit was saying what would happen to the horizontal distance moved by the grain if the separation of the plates was doubled and why (distance halved because force halved because E halved because d doubled?)
And then onto section C (which was a behemoth of a section in terms of numbers of questions, I thought)
13) Explain how brittle fracture occurs. I waffled about crack propagation and drew a diagram showing how stress is concentrated at the point?
14) a) Show that a wave would take less than four hours to go round the earth (convert wave speed into km per hr, work out circumference from the radius given, divide circumference by speed, comes out something like 3.7hours?)
b) show the two wavelengths were equal (both 6 km)
15) can't remember
16) something about natural frequency; talk about effects of resonance
17) work out that you need a length of about 100 (I got greater than 99) for the frequency you want
18) accelerating force question that was weird, threw me off a bit because it said explain why the accelerating force was small, and I could say why the acceleration was small, but this didn't necessarily make the force small, so yeah. Bit confused
19) Not sure what question this was?
20) Last bit was wordy, talking about damping, restoring forces, creation of eddy currents in opposition to direction of movement due to Lenz's law etc
And I think that's all I remember. Hope that helps :-)