cintaurus

New Member
I know I have mistakes in this but they're just what I put down as my answers
But I got:
1. D
2. B
3. D
4. D
5. B
6. A
7. B
8. D
9. A
10. C
11. B
12. B
13. A
14. D
15. A
16. A
17. C
18. C
19. A
20. C

iStudent

Well-Known Member
1D
2B
3D
4D
5B
6A
7B
8D
9A
10C
11B
12B
13C
14B
15A
16A
17B
18B (I got this wrong should be D)
19A
20D

hi im trash

Member
12/20. sooooooo... wonder what the cut off mark for band 5 will be.....

cintaurus

New Member
Shouldnt 18 be C since cathode ray is -ve charge hence the opposite or Left Hand palm rule?

iStudent

Well-Known Member
18 is D because force using LHPR is down
also the electric force needs to be up. So the electric field is down (reversed). I got it wrong be a use I misread magnetic field as electric field for the 2nd part of the q :L

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

sisabella

New Member
wheres the paper? someone post it

rated

Member
D
B
D
D
B
A
B
D
A
C
C (I got B but I changed it to C fk)
D
C
B
A
A
D
D
A
D

orcevalm

Member
16/20 im pretty sure

Kobweb

New Member
Anyone have a link of the paper?

IR

Active Member
1D
2B
3D
4D
5B
6A
7B
8D
9A
10C
11B
12B
13C
14B
15A
16A
17B
18B (I got this wrong should be D)
19A
20D
Should 12 be c? Since only the torque is effected by radial magnets? Not force? since the coil is always gonna be 90 degrees to magnetic field?

iStudent

Well-Known Member
Should 12 be c? Since only the torque is effected by radial magnets? Not force? since the coil is always gonna be 90 degrees to magnetic field?
It can't be C. By your logic the answer would be A (where radial magnets doesn't do anything). Also radial magnets eliminates the theta in f=bilsintheta (since it's always 90). Should be B because it shows it's constant. The second part of the question is sinusoidal like any other typical motor. (in your textbooks), with F=bilsintheta and theta changing causing the force to change as well.

This is a motor effect question right? You have current and your B field. So F=Bilsintheta is the formula you use?

edit: I don't know anymore. Can someone else explain why c?

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Member
1. D
2. B
3. D
4. D
5. D (should have been B :/)
6. A
7. A
8. D
9. A
10. C
11. B
12. B
13. C
14. B
15. A
16. A
17. C
18. D
19. A
20. B (Pretty much a guess for this one XD)

Member
Should 12 be c? Since only the torque is effected by radial magnets? Not force? since the coil is always gonna be 90 degrees to magnetic field?
Torque is the turning effect of a force

danielblarg

New Member
It can't be C. By your logic the answer would be A (where radial magnets doesn't do anything). Also radial magnets eliminates the theta in f=bilsintheta (since it's always 90). Should be B because it shows it's constant. The second part of the question is sinusoidal like any other typical motor. (in your textbooks), with F=bilsintheta and theta changing causing the force to change as well.

This is a motor effect question right? You have current and your B field. So F=Bilsintheta is the formula you use?

edit: I don't know anymore. Can someone else explain why c?
This is how I see it. In both diagrams, the wire PQ is always perpendicular to the magnetic field. The radial magnetic field only affects the torque, since with a parallel field not all of the force will be in the direction of rotation.
The magnitude of the force will be unaffected, always being F=BIlsintheta, where theta is always 90 degrees.

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iStudent

Well-Known Member
This is how I see it. In both diagrams, the wire PQ is always perpendicular to the magnetic field. The radial magnetic field only affects the torque, since with a parallel field not all of the force will be in the direction of rotation. But the magnitude of the force will be unaffected.
Ah I see. Didn't realise PQ was always perpendicular. Yup it's C

IR

Active Member
Ah I see. Didn't realise PQ was always perpendicular. Yup it's C
So how much do i get overall for mc? If i can get 20, i would be so happy bc I got 20 in chem.

danielblarg

New Member
I have different answers for 7 and 20 that I'm not sure about.
In 7, the coil should oppose the motion of the magnet by repelling it, which means it has a south pole at bottom and north pole at top, so the magnetic field goes from the top to the bottom, and the current goes clockwise, which is D.
In 20, after 2 seconds the horizontal velocity will still be u, and its at an angle of 45 degrees, so cos45 = u/v, v=u/cos45 = 1.41u, closest to B.

edit: I get 20 now, y velocity is u after 2 seconds so it is D
I can see 7 is B now.

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iStudent

Well-Known Member
So how much do i get overall for mc? If i can get 20, i would be so happy bc I got 20 in chem.
You got 10 as A?
I think it's C. Otherwise all correct