# June 2011 G485-Fields, Particles and Frontiers of PhysicsWatch

7 years ago
#721
(Original post by ChoYunEL)
18. Physicists are attempting to find a unified theory of the fundamental forces of nature.
(a) Name the four forces involved.
[4]

Gravitational force
Electrostatic force
Weak Nuclear force
Strong Nuclear force

(b) State the force involved in:
(i) holding quarks together in a proton.
[1]
Strong Nuclear force
(ii)  decay of a proton.
[1]
Weak Nuclear force allowing Quark flavours to change in Beta plus decay

(iii)  particle scattering by a nucleus.
[1]
Electrostatic?
(c) These forces are described by the exchange of particles. Name two of the exchange particles
involved in the situations listed in b).
[2]
Beta plus decay proton -> Neutron + Positron and a Neutrino
0
7 years ago
#722
(Original post by Kalamari Dave)
What equations should we know for tomorrow?
What constants should we know that aren't in the formula book (e.g. Parsec in km)?
How much of the spec would you say could come up as wordy questions?
How much have you revised?
How many marks do you need in this module to walk away with that grade?
All of them...
Learn all the definitions.
60-70% of the paper will be worded.
Everything I've wrote on TSR
I need an A
I need 115 UMS at least...
0
7 years ago
#723
(Original post by Oh my Ms. Coffey)
x
Correct.
Could you explain the 4 forces?
1
7 years ago
#724
(Original post by ChoYunEL)
18. Physicists are attempting to find a unified theory of the fundamental forces of nature.
(a) Name the four forces involved.
[4] Strong Nuclear, weak nuclear, gravitational, electrostatic

(b) State the force involved in:
(i) holding quarks together in a proton.
[1] Strong nuclear

(ii) decay of a proton.
[1] Weak nuclear

(iii) particle scattering by a nucleus.
[1] Electrostatic

(c) These forces are described by the exchange of particles. Name two of the exchange particles
involved in the situations listed in b).
[2] (These questions are from the old spec, I don't think we need to know about exchange particles.)
Hoping i've got this correct here haha

edit - beaten to it lol
0
7 years ago
#725
(Original post by Kalamari Dave)
What equations should we know for tomorrow?
What constants should we know that aren't in the formula book (e.g. Parsec in km)?
How much of the spec would you say could come up as wordy questions?
How much have you revised?
How many marks do you need in this module to walk away with that grade?
Me personally all the booklet ones indepth + the voltage across capacitors in series/parallel + N=(m/M)Na

50:50

Lots, for a long time.

D

<30 I think.
0
7 years ago
#726
Is the electrostatic and electromagnetic force the same thing?
0
7 years ago
#727
(Original post by Rosieretops)
I have the OCR checklist and it does say you need to know it qualitatively unfortunately and I wouldn't put it past them to ask horrible questions like that because they love it.
OOOOHHHHH NOOOOO!

And it would probably be just my luck for them to ask a 15 mark question on it. Â¬_Â¬.
0
7 years ago
#728
(Original post by ChoYunEL)
Correct.
Could you explain the 4 forces?
Strong nuclear is a force that binds nucleons together, it is an attractive force at long distances opposing the electrostatic force however at short distances it is repulsive, this is to prevent an atom collapsing in on itself.

Gravitational force acts between objects with mass it is an attractive force significantly weaker then the others at around 1x10^-36 on an atomic level, its effects cannot be shielded unlike the electrostatic force and its also not affected by any medium between two objects with mass unlike the electrostatic force.

Electrostatic force is a repulsive force that acts between particles with charge, it is much stronger then the gravitational force.

The weak nuclear force is the force which enables quark 'flavours' to change in beta plus and beta minus decay. Not sure on the rest of this.
0
7 years ago
#729
(Original post by XST)
Number of parsecs is inversely proportional to the angle of parallax, so as angle decreases, number of parsecs increases.

Divide the 1 parsec by the angle of parallax 0.275 and you get 3.64 parsecs.
Oh, of course!

I shall +rep you tomorrow.
0
7 years ago
#730
(Original post by M_I)
Is the electrostatic and electromagnetic force the same thing?

Simply put,
They are similar, Static involves charges, Magnetic involves movement
0
7 years ago
#731
(Original post by ChoYunEL)
All of them...
Learn all the definitions.

60-70% of the paper will be worded.
Everything I've wrote on TSR
I need an A
I need 115 UMS at least...

(Original post by Oh my Ms. Coffey)
Me personally all the booklet ones indepth + the voltage across capacitors in series/parallel + N=(m/M)Na

50:50

Lots, for a long time.

D

&lt;30 I think.

Was kinda hoping for specifics/exhaustive list!
Dear me. Lots of wordy OCR papers this June, eh? . I much prefer calculation based.
30 is an E That means you've got 100% so far

What is critical damping?
What is Flux?
What is Faraday's law?
Describe how the ultrasound scanner works
0
7 years ago
#732
What are possible synoptic links for this unit?
0
7 years ago
#733
(Original post by Kalamari Dave)
What is critical damping? - Resonance, looked for in G484
What is Flux? Magnetic Flux is looking at the equation, BAN, it's a scalar quantity
What is Faraday's law? The magnitude of e.m.f. is equal to the rate of change of magnetic flux linkage
Describe how the ultrasound scanner works - Piezoelectric effect, simply. Look at A-Scan and B-Scans
..
0
7 years ago
#734
(Original post by Kalamari Dave)
Was kinda hoping for specifics/exhaustive list!
Dear me. Lots of wordy OCR papers this June, eh? . I much prefer calculation based.
30 is an E That means you've got 100% so far
I need Â¬40 or summin.

What is critical damping?
What is Flux?
What is Faraday's law?
Describe how the ultrasound scanner works

Magnetic flux? - The product of Magnetic flux density B and Area A, measured in weber, Flux=BAcosx.

Faradays law states that Induced EMF is proportonal to rate of change of Magnetic flux linkage over rate of change of time.

Ultrasounds long but basically Piezoelectric crystals emit Ultrasound waves when an alternating voltage is applied, some waves are reflected and pass through depending on the acoustic impedance values of the materials it is passing through, if there is a big difference then most of the waves are reflected, if the medium has the same acoustic impedance none of the waves energy is reflected. A coupling medium is used when the acoustic impedance for two materials is very different - this is used between air and soft tissue and is usually a gel.

Im pretty weak on A-scan/B-scan can someone summarise them? I know A-scan is a depth scan.
0
7 years ago
#735
what time u lot goin sleep?
0
7 years ago
#736
(Original post by ChoYunEL)
..
Magnetic flux is BA, Magnetic flux linkage is BAN.
0
7 years ago
#737
(Original post by ChoYunEL)
..

(Original post by Oh my Ms. Coffey)
...
Cheers guys!
0
7 years ago
#738
I'm gonna go do a past paper, and some more revision.
Good luck for tomorrow (You probably won't need it!)
0
7 years ago
#739
(Original post by Oh my Ms. Coffey)
Im pretty weak on A-scan/B-scan can someone summarise them? I know A-scan is a depth scan.
A-Scan - Depth scan, looking at the time the crystal responds. Using depth scan, can find dimension of... blah
B-Scan - using an array of scanners to create a 2D/3D image. The echoes received determines the dimension etc .
0
7 years ago
#740
Can you define acoustic impedance using the equation and elaborating on the terms?
0
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