A friend and I have managed to remember these and *think* these are the answers. If there's anything we're missing, please do post!
SECTION A
1 Particle Physics [2]
a. (neutrino is) Lepton and Neutral
b. (proton is) Nucleon and Hadron
2 Scattering [3]
Particle deflected more
Because particle is moving slower and so force has more time to act on it
3 Graph of V vs r [3]
Field is uniform electric field
Field strength is the gradient
Gradient is constant, so E is constant
E = dV/dr = 3000/0.07 = 4.3 x 10^4 Vm-1
4 Alpha Safety [1, 2]
a. Mass is NOT conserved.
b. Agree (they are dangerous inside the body)
Alpha particles have high ionising ability, because they have a 2+ charge and can take electrons away from atoms easily.
They also have a low penetrating ability, so they can’t escape the body if ingested.
(ORA: Alpha particles highly ionising, but are stopped by a few cm of air/skin, so cannot get inside the body unless ingested/swallowed)
5 Transformers [1]
C (6 V and 0.36A)
6 Transformers (again) [2, 3]
a. flux is the same everywhere
flux density is double at point Z than at the sides/top of the core [must say double/twice/etc]
b. Crack introduces air gap
Air has much lower permeability compared to iron (about 1/8000th)
So overall permeance of core decreases
Φ is proportional to Λ, so flux increases
B is proportional to Φ, so flux density increases
7 Energy Levels [2]
ΔE = -1.5 eV + 3.4 eV = 1.9 eV = 3.04x10^-19 J
f = 4.6 x 10^14 Hz
λ = 6.5 x 10^-7 m
Lamda or frequency?
8 ???
SECTION B
9 Electric Fields [1, 1, 1, 1, 4, 2]
a i. field strength greater at X since field lines are closer together.
a ii.draw circle around the charge passing through X.
b i. Divide by 4, so (+)405 V
b ii. Divide by 16 so 6062.5 N
c. For Fig 9.3a, resultant force is 0 N, so E = F/q = 0 NC-1
(OR calculations and statement: Eleft = Eright, so no resultant field strength)
For Fig 9.3b, resultant force is 2 x kQq/r2 = 6.3 x 10^7 x q N
So E = F/q = 6.3 x 10^7 NC-1
d. For +ve charge, Velec = +kQ/r
For -ve charge, Velec = -kQ/r
So total V = +kQ/r - kQ/r = 0
10 Motors
a. F = BIL = ???
b. If L is halved, F is halved (since F is proportional to L), so the acceleration halves, and the motor moves more slowly. --QUERY: could be as F halves, but m halves, acceleration is the same, so no change in rate.
c. max NΦ = NBA = 0.0243 Wb-turns
d. average e.m.f = d(NΦ)/dt = 0.12(15) V
e. When moving, the motor is experiencing a change of flux linkage, and so an emf is induced.
Current is induced too, and by Lenz's law the induced current must flow in such a way that it opposes the change creating it, so it acts in the opposite direction to the current already there.
So the resultant current decreases while the motor turns.
When the motor is jammed (not moving) there is no change in flux linkage, so no emf is induced, and so no opposing current is induced. This means the current remains as it is (higher than when rotating).
11 Particles in Magnetic Fields [1?, 1, 2, 4]
a. Force acts perpendicular to direction of motion, so motion is circular
b. r = mv/Bqc. Alpha particle is much heavier than beta particle, so you would expect the radius of the circular path it takes to be much larger, as predicted in the diagram.
Gamma straight because it is uncharged, so is unaffected by the magnetic field.
d. rα = 0.20625/B
rβ = 0.0011375/B
rβ is 180 times smaller than rα, so diagram incorrect in the sense that it only shows slight difference in radius.
12 Radiation [1, 2, 3, 2, 3]
a. LHS: Lepton number = 0 [nuclei have no lepton number]
RHS: Lepton number = 0 + 1 - 1 = 0 [nuclei]
So lepton number conserved.
b. λ = 1.0 x 10-6 s-1A0 = 5.49 x 10^5 Bq
c. A12 weeks = 394 Bq [345ish if you use their values)
d. Absorbed dose = 0.89 Gy
Assumption is all the beta particles are absorbed by the gland
e. γ rays have high penetrating ability, so can escape from body
Radiation can therefore be detected by external sensors to track movement through body.
γ rays have low ionising ability, so do not cause much damage (as long as not too much is given)
Iodine-131 not used anymore, because the half-life is too long.
The total absorbed dose by the thyroid gland due to 131-I was too high (so increases risk of cancer by unacceptable amounts).
SECTION C
13 Lenses [1, 2]
a. magnification = v/u = 89/-5.3 = (-)16.79… = (-)17x
b. power = 200 D
14 Imaging [2, 2]
a. 5.2 x 10-7 m
b. Approx. 270 lenses in picture, so 20,000 lenses in total, but they will probably accept values in a large range
c. A part c????
15 Gases and Boltzmann Factor [3, 4]
a. ??? something here ???
b. Number of particles per cubic cm was 2.4 x 10^9
c. I is proportional to eE/kT... Boltzmann factor can be used because...
BF is proportion of electrons with enough energy to escape.
Rate of electron release is proportional to BF
Current is proportional to number of electrons flowing (since current is rate of flow of charge)
So current is proportional to BF
d. T = 2310 K
16 B Fields [2, 3]
a. N = 3800 turns [show that]
b. 380-390 V (allow range as ft from a)
17 Wavelength of Electrons
a. i. E = 6.4 x 10^-15 J
ii. p = 1.1 x 10^-22 kgms-1
b. λ = 6.1 x 10^-12 m
Resolution = 3.1 x 10^-12 m
c. number of electrons needed to change temperature by 1 K = 1.8 x 10^6
18 Deflecting Electrons [1, 4, 2]
a. E = 1.1 x 10^5 Vm-1
b. L = 0.027m
c. E is constant everywhere (it is a uniform field) so force is the same everywhere / process in (b) is the same everywhere.
19 Relativity [3]
γ = 1.39
v = 2.1 x 10^8 ms-1