Multiple choice answers (3 Viewers)

[00iCon]

BCCCCACCABDDACA

can someone mark me

i choked and i dont wanna do it

Q1 wrong
2 wrong
4 wrong
... need i say more?

 

[untouchablecuz]

Q1 wrong
2 wrong
4 wrong
... need i say more?

 

[buildabridge]

1 C
2 A
3 C
4 D
5 C <too easy, at first i thought it was talking about force from solar wind
6 A
7 C
8 C
9 C
10 B
11 B
12 D
13 B
14 C
15 A
Those are my answers and they're the exact same as the guy behind me :S

I got the same as you except for 11 which I thought was D, I could be wrong though. Multiple choice was quite tricky I thought.

 

[00iCon]

Its jsut a hell of a lot different to my answers... i could be wrong.
but Q1 is DEFINATELY (C)
just wiki it

 

[Ostentatious]

I got the same as you except for 11 which I thought was D, I could be wrong though. Multiple choice was quite tricky I thought.

Same here for 11 D, I really think F of AB should be a sine curve.

 

[00iCon]

I got the same as you except for 11 which I thought was D, I could be wrong though. Multiple choice was quite tricky I thought.

11 is definately NOT D. the force on the wire is constant and up, until the commutator switches it.

 

[08joel08]

I got the same as you except for 11 which I thought was D, I could be wrong though. Multiple choice was quite tricky I thought.

in that case i got the same as you, i now know nine is (a) i didnt read electrons, and assumed current also i got (a) for 13

is anyone on my side that 13 is (a)?
my reasons are that electrons dont experience attraction to one another, and that even if ure gonna call them bonding together attraction its not as a result of low temps and is a result of low temps affect on the lattice, are people saying that (a) is wrong because there are still small lattice vibrations? from my understanding a metal in superconducting has movement but no vibrations can anyone explain/elaborate?

 

[Ostentatious]

11 is definately NOT D. the force on the wire is constant and up, until the commutator switches it.

The wire is perpendicular to the magnetic field, at that moment in time the motor would rely on momentum to push it to get it started, where torque is also at a maximum. Plus, the force on AB is actually down, I'm pretty sure of it.

EDIT: Just noticed the arrow indicating it's up, but the current indicates otherwise?

 

[shady145]

11 is definately NOT D. the force on the wire is constant and up, until the commutator switches it.

force is proportional to sintheta... therefore its D

 

[Ostentatious]

in that case i got the same as you, i now know nine is (a) i didnt read electrons, and assumed current also i got (a) for 13

is anyone on my side that 13 is (a)?
my reasons are that electrons dont experience attraction to one another, and that even if ure gonna call them bonding together attraction its not as a result of low temps and is a result of low temps affect on the lattice, are people saying that (a) is wrong because there are still small lattice vibrations? from my understanding a metal in superconducting has movement but no vibrations can anyone explain/elaborate?

The lattice still has small vibrations at low temperatures.

According to BCS theory, an electron will attract protons behind it, causing a small lattice distortion that creates a small positive field, attracting another electron. The electrons then exchange phonons and move as one particle, contributing to superconductivity unimpeded by the lattice, and the process continues - hence Cooper Pairs.

 

[00iCon]

well, in 11, (D) starts at zero, so wrong. its not asking for the force perpendicular to the coil, but the force ONLY on AB.

for 13 i got B but im not too sure...

 

[00iCon]

The lattice still has small vibrations at low temperatures.

According to BCS theory, an electron will attract protons behind it, causing a small lattice distortion that creates a small positive field, attracting another electron. The electrons then exchange phonons and move as one particle, contributing to superconductivity unimpeded by the lattice, and the process continues - hence Cooper Pairs.

the way i tought was that the Cooper pairs actually CREATE the vibrations, so not A. not C or D obviously. so B.

 

[shady145]

well, in 11, (D) starts at zero, so wrong. its not asking for the force perpendicular to the coil, but the force ONLY on AB.

for 13 i got B but im not too sure...

true... i fell into that trap in trial dammit

 

[Ostentatious]

I don't get it? Isn't the force on a current carrying conductor F=BIlsin(theta)? That would mean force is proportional to the sine curve and thus be one.

 

[Macdwg]

This is what i have.

1. c
2. a
3. c
4. d
5. c
6. a
7. c
8. c
9. c
10. b
11. b
12. d
13. b
14. c
15. a

 

[kieranjackson91]

force is proportional to sintheta... therefore its D

lol ummm yeah but what is theta? hmm i wonder if it could be? yes it its! the angle between the conducter and the field which is :O always 90 degrees hence :O sintheta =1 hence answer is B (current switches)

 

[Ostentatious]

No, the angle isn't 90 it is 0. sin0 = 0. Even with your reasoning you're wrong, because torque would have to be a cos curve with your reasoning. torque is not current. With your reasoning, the answer would be A, because B, I and l remain constant.

EDIT: OK I got it, the angle is 90, making the answer A.

EDIT2: I think I got jackson's answer now, problem solved ^_^

 

[shady145]

lol ummm yeah but what is theta? hmm i wonder if it could be? yes it its! the angle between the conducter and the field which is :O always 90 degrees hence :O sintheta =1 hence answer is B (current switches)

yea i know

 

[kieranjackson91]

1.C
2.A
3.C
4.D
5.B (I thought too much about it, should be C)
6.A
7.C
8.C
9.A
10.B
11.B
12.D
13.B
14.C
15.A

14/15 dam

 

[max powers]

I hope 11. is B

I put that only because I got the exact question wrong the day before (what luck, huh).