# G485 2014 JUNE Unofficial mark schemeWatch

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#1
G485 PHYSICS UNIT 5 : Fields, Particles and Frontiers of Physics
UNOFFICIAL MARK SCHEME
Teachercol MS with all questions: http://www.thestudentroom.co.uk/show...highlight=G484
100 ums: 90 A*: 83 A: 76 B: 70 C:
Q1 ) [Electric fields] total: 7
a)

(i) fields lines directed at negative charge (2)
(ii) B has more charge (what did everyone say for this and why?) (2)
(b)
(i) graph [needs discussion] (3)
(ii) why is the ratio the same?: because they both follow inverse square law (1)

Q2 ) [Particle in fields ] total: 9
a)
force exerted by field is at right angles to velocity (1)
(ii) As the force is at right angles, no work is done in increasing the speed. KE=0.5mv^2 (1)
(b)
(i) mv = 9.6x10^-24 (3)
(ii) KE = 6.98x10^-21 (2)
(iii) Electric field exerts a horizontal force directed to the right. spirals to the right with the radius of the circle constantly increasing (2) needs discussion

Q3 ) [Particle physics] total: 17
a)
(i) C (1)
(ii) Q=0 (1)
(b)
(i) X = proton ? (1)
(ii) Neutron decay Proton with 1 mass no. and 1 pro no. and anti-neutrino (2)
(iii) half life of a free neutron : time it takes for a neutron to decay??? needs discussion (1)

Q4) [capacitors] total: 14
a)
(i) time constant: the time it takes for a capacitor's charge to decrease to 37% of its initial value (1)
(ii) any factor of 5 (1)
(iii) time constant = 2.17 (3) (please note you have to HALF diameter)
(iv) Electrons travel around the circuit in an anti-clockwise motion.
They enter plate Y causing it to become negatively charge.
This repels electrons off plate X giving it positive charge.
Electrons enter plate Y as they leave plate X therefore same charge but opposite directions. (3)
(iv) incr in temp = 3.2 (4)
(v) Double V cause quadruple Energy therefore incr in temp increases by a factor of 4 (2)

Q ) [Electromagnetic induction] total:
a)
Faradays law: Magnitude of the induced emf is proportional to the rate of change of magnetic flux linkage (1)
(ii) Using energy explain...: (1) [will update later if i obtain the answer]
(iii) No emf is induced as the coil is moving parallel (with) the field rather than perpendicular to it (1)
(b) graph (3) needs discussion

Q ) [Fusion] total:
a)
why is mass different for deuterium and nucleons: When deuterium is split, some of its mass is converted to energy so the nucleons will have a higher total mass. The mass converted can be found with E=mc^2 (2)

b (i) Force between nuclei = 2.3N (2)
(ii) Temperature for fusion: 5.41x10^8 (3?)
(iii) fusion can occur at lower temperatures as the average KE is just an average. therefore some nuclei will have a faster KE than the average and will fuse. Quantum tunneling (2)
(iv) It is harder to fuse with helium as it has a greater charge thus the electric static repulsion between the nuclei is higher. A higher KE is required to overcome this increase thus it requires higher temperatures (2)

Q) [Energy levels and x rays] total:
a)
as this was unit 2 I didnt do too well in this section. can someone define energy level for me and the other stuff that came up
(i) Energy level: an energy level is a quantized energy of a bound quantum mechanical state (1) [source: google]
()An increase in voltage doubles max KE thus halves min wavelength (2)
b) fraction of x ray absorbed = 0.89 (3)
(ii) Bone and muscle as their higher attenuation coefficient means they absorb x rays better thus increasing contrast as they are clearer in a scan (2)

Q ) [Nuclear power] total:
a)
how is fission in a power plant induced?: Because they split because of external interactions. A slow moving neutron is absorbed by a uranium atom causing it to become unstable and split into smaller nuclei and neutrons (2?)
(b) uses of moderator and control rods (4):
• Moderators turn fast moving neutrons into thermal neutrons
• Neutrons collide with the water molecules (or carbon atoms) causing them to transfer their kinetic energy thus lowering their speed
• Thermal neutrons are required as they have a higher chance of inducing futher fission (chain reaction)
• Control rods (boron) absorb neutrons reducing the amount of fissions keeping the reactor controlled and safe.
• Neutrons absorb neutrons to allow only one neutron from each fission reaction to induce further fission

Q ) [medical physics] total: 7
a)
(i) B-scan (3)
• An array of transducers send ultrasound into the body at different angles and in pulses
• The ultrasound is reflected at boundaries in the boundary and enters the transducer
• The fraction of ultrasound reflected determines the material at the boundaries
• This fraction is determined by the acoustic impedance of the material at the boundaries

(b) PET scan (4)
• A positron emitting tracer is injected into the body
• the positions are annihilated by electrons in the body
• producing two gamma photons going in opposite dirrections
• a ring of detectors pick up the gamma photons and send signals to a computer
• A computer can determine the location of annihilation by analysing the time delay between gamma photon detection

Q9) [Hubble's law] total:
a)
density = something x 10^21 needs discussion (did anyone get 2.21x10^18? (2)
(ii) ratio of g= 1.36 x 10^10? (2)
(b) Parallax= 0.38 (3)
(ii) wave length = 2.5x10^-3 (2)[may rearrange later]
(iii) You can not use hubbles law because: the star is moving towards us not away.
Hubbles law refers to galaxies not stars. (1)

Q10 ) [The universe] total: 8
a)
Cosmological principal: There is no centre to the universe. the universe is expanding and is finite. the universe is isotropic and homogeneous (2)

(b) CMR: Is isotropic and homogenous with a temp of 2.7K.
It is thought that it originated from a infinitely hot and small point which is the start of the big bang.
the CMR is expanding and cooling, just as big bang predicted. the annihilation of quarks stated in the big bang is said to have produced the CMR (3)

(c) Age = 1.36 x 10^10 (3)

notes:
[fractions of wavelength from a star? Activity question and mass of C-14? E released from fusion = 18MeV? Half life = 5700 years]
10
#2
having a hard time remembering question numbers and questions.

please state the questions that came up and if u can its question number
(was easier with unit 4, but unit 5 is 100 marks so much harder for me to moderate :P)
0
5 years ago
#3
(Original post by nmanvi)
having a hard time remembering question numbers and questions.

please state the questions that came up and if u can its question number
There's was a question based on finding the change in mass in the nuclear physics section.

Finding the mass of C-14

Finding the energy of B in the X-Ray section. I think question 7
0
5 years ago
#4
For time constanst I got 0.54 or something...
0
5 years ago
#5
Yes for the time constant i got 0.5 something
0
#6
(Original post by henryt9956)
Yes for the time constant i got 0.5 something

(Original post by Jake68910)
For time constanst I got 0.54 or something...
Thanks for your replies. can anyone else give me their values?
by the way guys did you use half the diameter?
0
5 years ago
#7
(Original post by henryt9956)
Yes for the time constant i got 0.5 something
I got 2. something.
0
5 years ago
#8
(Original post by nmanvi)
G485 PHYSICS UNIT 5 : Fields, Particles and Frontiers of Physics
UNOFFICIAL MARK SCHEME
IN CONSTRUCTION: Please tell me if i get anything wrong and i will query the answer and update the mark scheme. Tell me questions and answers if i ask for it. i will very likely get the a)/(i) order wrong, soz.
I will very likely get the a)/(i) order wrong sorry.
100 ums: A*: A: B: C:
Q1 ) [Electric fields] total: 7
a)

(i) fields lines directed at negative charge (2)
(ii) B has more charge (what did everyone say for this and why?) (2)
(b)
(i) graph [needs discussion] (3)
(ii) why is the ratio the same?: because they both follow inverse square law (1)

Q2 ) [Particle in fields ] total: 9
a)
force exerted by field is at right angles to velocity (1)
(ii) As the force is at right angles, no work is done in increasing the speed. KE=0.5mv^2 (1)
(b)
(i) mv = 9.6x10^-24 (3)
(ii) KE = 6.98x10^-21 (2)
(iii) spirals to the right with the radius of the circle constantly increasing??? (2) needs discussion

Q3 ) [Particle physics] total: 17
a)
(i) C (1)
(ii) Q=0
(b)
Proton with 1 mass no. and 1 pro no. and anti-neutrino (2)
(ii) half life of a free neutron : time it takes for a neutron to decay??? needs discussion (1)

Q ) [capacitors] total: 13?
a)
(i) any factor of 5 (1)
(ii) time constant = 2.61 (3)
(iii) Electrons travel around the circuit in an anti-clockwise motion.
They enter plate Y causing it to become negatively charge.
This repels electrons off plate X giving it positive charge.
Electrons enter plate Y as they leave plate X therefore same charge but opposite directions. (3)
(iv) incr in temp = 3.4 ?
(v) Double V cause quadruple Energy therefore incr in temp increases by a factor of 4 (2)

Q ) [Fusion] total:
a)
why is mass different for deuterium and nucleons: When deuterium is split, some of its mass in converted to energy so the nucleons will have a lower total mass. The mass converted can be found with E=mc^2 (2) [if you have a better answer please say]

Q1 ) [Nuclear power] total:
a)
how is fission in a power plant induced?: Because they split because of external interactions. A slow moving neutron is absorbed by a uranium atom causing it to become unstable and split into smaller nuclei and neutrons (2?)

(b) uses of moderator and control rods (4):
• Moderators turn fast moving neutrons into thermal neutrons
• Neutrons collide with the water molecules (or carbon atoms) causing them to transfer their kinetic energy thus lowering their speed
• Thermal neutrons are required as they have a higher chance of inducing futher fission (chain reaction)
• Control rods (boron) absorb neutrons reducing the amount of fissions keeping the reactor controlled and safe.
• Neutrons absorb neutrons to allow only one neutron from each fission reaction to induce further fission

Q ) [medical physics] total: 7
a)
(i) B-scan (3)
• An array of transducers send ultrasound into the body at different angles and in pulses
• The ultrasound is reflected at boundaries in the boundary and enters the transducer
• The fraction of ultrasound reflected determines the material at the boundaries
• This fraction is determined by the acoustic impedance of the material at the boundaries

(b) PET scan (4)
• A positron emitting tracer is injected into the body
• the positions are annihilated by electrons in the body
• producing two gamma photons going in opposite dirrections
• a ring of detectors pick up the gamma photons and send signals to a computer
• A computer can determine the location of annihilation by analysing the time delay between gamma photon detection

Q ) [The universe] total: 8
a)
Cosmological principal: There is no centre to the universe. the universe is expanding and is finite. the universe is isotropic and homogeneous (2)

(b) CMR: Is isotropic and homogenous with a temp of 2.7K.
It is thought that it originated from a infinitely hot and small point which is the start of the big bang.
the CMR is expanding and cooling, just as big bang predicted. the annihilation of quarks stated in the big bang is said to have produced the CMR (3)

(c) Age = 1.36 x 10^10 (3)
About the Deutrineum, I mentioned the mass defect, and I also said its mass would be less than the nucleons because of the binding energy required to seperate the nucleons, and then i just said E = mc squared.
0
5 years ago
#9
(Original post by ThatManAlex)
I got 2. something.
R was 54.2... CR= 54.2 x 0.01
0
5 years ago
#10
(Original post by nmanvi)
Thanks for your replies. can anyone else give me their values?
by the way guys did you use half the diameter?
must have missed that it was the diameter
0
#11
(Original post by ThatManAlex)
About the Deutrineum, I mentioned the mass defect, and I also said its mass would be less than the nucleons because of the binding energy required to seperate the nucleons, and then i just said E = mc squared.
Yea that sounds fine to me
0
5 years ago
#12
(Original post by Jake68910)
R was 54.2... CR= 54.2 x 0.01
I got that first time then realised they gave you wrong unit for something. Like diameter instead of radius.
Every question they gave needing a radius, the diameter was given bar like one question.

Posted from TSR Mobile
1
5 years ago
#13
(Original post by nmanvi)
G485 PHYSICS UNIT 5 : Fields, Particles and Frontiers of Physics
UNOFFICIAL MARK SCHEME
IN CONSTRUCTION: Please tell me if i get anything wrong and i will query the answer and update the mark scheme. Tell me questions and answers if i ask for it. i will very likely get the a)/(i) order wrong, soz.
I will very likely get the a)/(i) order wrong sorry.
100 ums: A*: A: B: C:
Q1 ) [Electric fields] total: 7
a)

(i) fields lines directed at negative charge (2)
(ii) B has more charge (what did everyone say for this and why?) (
(Things to add) was about drawing the resultant electric field strength from a distance d from A.

(b)

(i) graph [needs discussion] (3)
(ii) why is the ratio the same?: because they both follow inverse square law (1)

Q2 ) [Particle in fields ] total: 9
a)
force exerted by field is at right angles to velocity (1)
(ii) As the force is at right angles, no work is done in increasing the speed. KE=0.5mv^2 (1)
(b)
(i) mv = 9.6x10^-24 (3)
(ii) KE = 6.98x10^-21 (2)
(iii) spirals to the right with the radius of the circle constantly increasing??? (2) needs discussion

Q3 ) [Particle physics] total: 17
a)
(i) C (1)
(ii) Q=0
(b)
Proton with 1 mass no. and 1 pro no. and anti-neutrino (2)
(ii) half life of a free neutron : time it takes for a neutron to decay??? needs discussion (1
(things to add) work out the force on the lithium particle
work out the mean temperature of the hydrogen gas, assuming it's an ideal gas.
why the actual temperature , in practice, required is less than the answer above.
Chnage in mass after fusion.
why the probability of helium and deterium is less than deterium-lithium fusion.
Q ) [capacitors] total: 13?
(Things to add) definition of time constant
a)
(i) any factor of 5 (1)
(ii) time constant = 2.61 (3) (please note you have to HALF diameter)
(iii) Electrons travel around the circuit in an anti-clockwise motion.
They enter plate Y causing it to become negatively charge.
This repels electrons off plate X giving it positive charge.
Electrons enter plate Y as they leave plate X therefore same charge but opposite directions. (3)
(iv) incr in temp = 3.4 ?
(v) Double V cause quadruple Energy therefore incr in temp increases by a factor of 4 (2)

Q ) [Fusion] total:
a)
why is mass different for deuterium and nucleons: When deuterium is split, some of its mass in converted to energy so the nucleons will have a lower total mass. The mass converted can be found with E=mc^2 (2) [if you have a better answer please say]

(unknown) (i) Temperature for fusion: 5.41x10^8 (3?)
(ii) fusion can occur at lower temperatures as the average KE is just an average. therefore some nuclei will have a faster KE than the average and will fuse. Quantum tunneling (2)
(iii) It is harder to fuse with helium as it has a greater charge thus the electric static repulsion between the nuclei is higher. A higher KE is required to overcome this increase thus it requires higher temperatures (2)

Q1 ) [Nuclear power] total:
a)
how is fission in a power plant induced?: Because they split because of external interactions. A slow moving neutron is absorbed by a uranium atom causing it to become unstable and split into smaller nuclei and neutrons (2?)

(b) uses of moderator and control rods (4):
• Moderators turn fast moving neutrons into thermal neutrons
• Neutrons collide with the water molecules (or carbon atoms) causing them to transfer their kinetic energy thus lowering their speed
• Thermal neutrons are required as they have a higher chance of inducing futher fission (chain reaction)
• Control rods (boron) absorb neutrons reducing the amount of fissions keeping the reactor controlled and safe.
• Neutrons absorb neutrons to allow only one neutron from each fission reaction to induce further fission

Q ) [medical physics] total: 7
a)
(i) B-scan (3)
• An array of transducers send ultrasound into the body at different angles and in pulses
• The ultrasound is reflected at boundaries in the boundary and enters the transducer
• The fraction of ultrasound reflected determines the material at the boundaries
• This fraction is determined by the acoustic impedance of the material at the boundaries

(b) PET scan (4)
• A positron emitting tracer is injected into the body
• the positions are annihilated by electrons in the body
• producing two gamma photons going in opposite dirrections
• a ring of detectors pick up the gamma photons and send signals to a computer
• A computer can determine the location of annihilation by analysing the time delay between gamma photon detection

(Things to add) question 9. The binary star system Sirius A and Sirius B. Work out the density of s
sirius B.
work out ratio of the gravitational feild strengths of the sun to Sirius B.
Use the ratios of their diameters squared.
cant remember what was afterwards..
Q ) [The universe] total: 8
a)
Cosmological principal: There is no centre to the universe. the universe is expanding and is finite. the universe is isotropic and homogeneous (2)

(b) CMR: Is isotropic and homogenous with a temp of 2.7K.
It is thought that it originated from a infinitely hot and small point which is the start of the big bang.
the CMR is expanding and cooling, just as big bang predicted. the annihilation of quarks stated in the big bang is said to have produced the CMR (3)

(c) Age = 1.36 x 10^10 (3)
check my edits above
1
5 years ago
#14
(Original post by nmanvi)
(ii) You can not use hubbles law because: the star is moving towards us not away.
Hubbles law refers to GALAXIES not stars. (1)
Last question in 9:

I said it's because the velocity is a relative velocity (Relative to us) and thus it's actually velocity will be different as we are also moving with a certain Veloctiy.
0
#15
(Original post by Jake68910)
Last question in 9:

I said it's because the velocity is a relative velocity (Relative to us) and thus it's actually velocity will be different as we are also moving with a certain Veloctiy.
No sorry that probably wont get you a mark
0
5 years ago
#16
(Original post by nmanvi)
No sorry that probably wont get you a mark
Well in my answer I did say its relative velocity would have reduced as it is travelling towards us... but I still think the answer is to do with "Relative velocity" because I've never seen them call it Relative Velocity before in a question...
0
#17
(Original post by Jake68910)
Well in my answer I did say its relative velocity would have reduced as it is travelling towards us... but I still think the answer is to do with "Relative velocity" because I've never seen them call it Relative Velocity before in a question...
The reason you can not use hubbles constant is because it doesn't work with stars. even if the relative velocity thing was corrected it still wouldnt work. plus it wasnt even moving away from earth

sorry man
0
5 years ago
#18
150 - 86
135 - 78
120 - 70
105 - 63
90 - 56
Just a guess.

Posted from TSR Mobile
0
5 years ago
#19
(Original post by nmanvi)
G485 PHYSICS UNIT 5 : Fields, Particles and Frontiers of Physics
UNOFFICIAL MARK SCHEME
IN CONSTRUCTION: Please tell me if i get anything wrong and i will query the answer and update the mark scheme. Tell me questions and answers if i ask for it. i will very likely get the a)/(i) order wrong, soz.
I will very likely get the a)/(i) order wrong sorry.
100 ums: A*: A: B: C:
Q1 ) [Electric fields] total: 7
a)

(i) fields lines directed at negative charge (2)
(ii) B has more charge (what did everyone say for this and why?) (2)
(b)
(i) graph [needs discussion] (3)
(ii) why is the ratio the same?: because they both follow inverse square law (1)

Q2 ) [Particle in fields ] total: 9
a)
force exerted by field is at right angles to velocity (1)
(ii) As the force is at right angles, no work is done in increasing the speed. KE=0.5mv^2 (1)
(b)
(i) mv = 9.6x10^-24 (3)
(ii) KE = 6.98x10^-21 (2)
(iii) spirals to the right with the radius of the circle constantly increasing??? (2) needs discussion

Q3 ) [Particle physics] total: 17
a)
(i) C (1)
(ii) Q=0
(b)
(i) X = proton ?
(ii) Neutron decay Proton with 1 mass no. and 1 pro no. and anti-neutrino (2)
(iii) half life of a free neutron : time it takes for a neutron to decay??? needs discussion (1)

Q ) [capacitors] total: 14
a)
(i) time constant: the time it takes for a capacitor's charge to decrease to 37% of its initial value (1)
(ii) any factor of 5 (1)
(iii) time constant = 2.61 (3) (please note you have to HALF diameter)
(iv) Electrons travel around the circuit in an anti-clockwise motion.
They enter plate Y causing it to become negatively charge.
This repels electrons off plate X giving it positive charge.
Electrons enter plate Y as they leave plate X therefore same charge but opposite directions. (3)
(iv) incr in temp = 3.2 (4)
(v) Double V cause quadruple Energy therefore incr in temp increases by a factor of 4 (2)

Q ) [Fusion] total:
a)
why is mass different for deuterium and nucleons: When deuterium is split, some of its mass in converted to energy so the nucleons will have a lower total mass. The mass converted can be found with E=mc^2 (2) [if you have a better answer please say]
() Force between nuclei = 2.3N (2)

(unknown) (i) Temperature for fusion: 5.41x10^8 (3?)
(ii) fusion can occur at lower temperatures as the average KE is just an average. therefore some nuclei will have a faster KE than the average and will fuse. Quantum tunneling (2)
(iii) It is harder to fuse with helium as it has a greater charge thus the electric static repulsion between the nuclei is higher. A higher KE is required to overcome this increase thus it requires higher temperatures (2)

Q ) [Nuclear power] total:
a)
how is fission in a power plant induced?: Because they split because of external interactions. A slow moving neutron is absorbed by a uranium atom causing it to become unstable and split into smaller nuclei and neutrons (2?)

Q9) [Energy levels and x rays] total:
a)
as this was unit to didnt do well in this section. can someone define energy level for me and the other stuff that came up
b) fraction of x ray absorbed = 0.89 (3)
(ii) Bone and muscle as their higher attenuation coefficient means they absorb x rays better thus increasing contrast as they are clearer in a scan (2)

(b) uses of moderator and control rods (4):
• Moderators turn fast moving neutrons into thermal neutrons
• Neutrons collide with the water molecules (or carbon atoms) causing them to transfer their kinetic energy thus lowering their speed
• Thermal neutrons are required as they have a higher chance of inducing futher fission (chain reaction)
• Control rods (boron) absorb neutrons reducing the amount of fissions keeping the reactor controlled and safe.
• Neutrons absorb neutrons to allow only one neutron from each fission reaction to induce further fission

Q ) [medical physics] total: 7
a)
(i) B-scan (3)
• An array of transducers send ultrasound into the body at different angles and in pulses
• The ultrasound is reflected at boundaries in the boundary and enters the transducer
• The fraction of ultrasound reflected determines the material at the boundaries
• This fraction is determined by the acoustic impedance of the material at the boundaries

(b) PET scan (4)
• A positron emitting tracer is injected into the body
• the positions are annihilated by electrons in the body
• producing two gamma photons going in opposite dirrections
• a ring of detectors pick up the gamma photons and send signals to a computer
• A computer can determine the location of annihilation by analysing the time delay between gamma photon detection

Q9) [Hubble's law] total:
a)
density = something x 10^21 needs discussion (2)
(ii) ratio = ? (2)
(b) Parallax= 0.38 (3)
(ii) You can not use hubbles law because: the star is moving towards us not away.
Hubbles law refers to GALAXIES not stars. (1)

Q10 ) [The universe] total: 8
a)
Cosmological principal: There is no centre to the universe. the universe is expanding and is finite. the universe is isotropic and homogeneous (2)

(b) CMR: Is isotropic and homogenous with a temp of 2.7K.
It is thought that it originated from a infinitely hot and small point which is the start of the big bang.
the CMR is expanding and cooling, just as big bang predicted. the annihilation of quarks stated in the big bang is said to have produced the CMR (3)

(c) Age = 1.36 x 10^10 (3)
The time constant question was 4 I think, and I think the time constant was 2.17?

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0
#20
(Original post by mb07)
The time constant question was 4 I think, and I think the time constant was 2.17?

Posted from TSR Mobile
Thanks will check
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