Want to compare multiple-choice answers? (1 Viewer)

[passion89]

8.A - because maximum FLUX goes through the loop when its perpendicular to field

Yup 8 is A even went to check it later with the teacher and textbook.

 

[zeek]

Luckily i wrote mine down on the question sheet aswell
This is what i got:

1. C [the values of g changes due to lithosphere density etc.]
2. B [A mass in circular motion experiences tangential velocity]
3. D
4. B [Acceleration on a projectile is constant at 9.8m/s²]
5. D [Using Keppler's formula]
6. A
7. C [Using formula]
8. A [Maximum flux is experienced when it is perpindicular to the field]
9. D [The generator doesn't have a split ring commutator so its not B and D, motor effect applies so its not A]
10. C [Using the ratio of voltages to coil turns]
11. A
12. C
13. D
14. C [Using the formula]
15. A

EDIT: For number 10 in the multiple choice, the two graphs had to comply with Lenz's law .: you can safely eliminate B and D as they both have positive values and violate the principle of conservation of energy. A can also be eliminated as the same 'voltage pattern' is not replicated and it also has positive voltage which should not occur if the primary coil did not experience negative volatge, .: it is D, well thats wat i think anyways

 

[ianc]

Luckily i wrote mine down on the question sheet aswell
This is what i got:

1. C [the values of g changes due to lithosphere density etc.]
2. B [A mass in circular motion experiences tangential velocity]
3. D
4. B [Acceleration on a projectile is constant at 9.8m/s²]
5. D [Using Keppler's formula]
6. A
7. C [Using formula]
8. A [Maximum flux is experienced when it is perpindicular to the field]
9. D [The generator doesn't have a split ring commutator so its not B and D, motor effect applies so its not A]
10. C [Using the ratio of voltages to coil turns]
11. A
12. C
13. D
14. C [Using the formula]
15. A

I got exactly the same except for 10, which i put A

Also, even though I put D for 9 im not sure if its right....

 

[4DOGS]

1. c
2. b
3. d
4. b
5. d
6. a
7. c - you had to use trig to find the diagonal distance to use as (l)
8. B
9. d
10. d - isnt a transformer ac current so theres a changing voltage?
11. a
12. c
13. d
14. c
15. a - guessed this one

i think i got about 12 right that i am confident with

 

[zeek]

Also, even though I put D for 9 im not sure if its right....

Even if you apply the formula for EMF on this generator and then graph it you should get a sinusoidal pattern because there is nothing in that diagram to tell me that the current is being reversed every half turn.

EDIT: oops i think ur right for 10, because once the current is turned off the voltage in the secondary coil should become positive.

 

[shinji]

for 14 i just used logic. lol

if u wanan double electric field strength, why would u wanna double the distance?
sooo hence, double the voltage

 

[bboyelement]

for 10 i got d as well because transformers are AC and the amplitude increases when you have a higher voltage ... so yeh i cant see how its dc...

 

[XcarvengerX]

for 14 i just used logic. lol

if u wanan double electric field strength, why would u wanna double the distance?
sooo hence, double the voltage

But the plates changed from aluminium to copper. Isn't that a problem?

 

[bboyelement]

But the plates changed from aluminium to copper. Isn't that a problem?

no because it goes what new arrangement can be used ... the only two that would have been correct was perpex and copper... but perpex doesnt conduct electricity so i cant see how that works

 

[shinji]

@XcarvengerX: what bboy said

 

[vnblueberry]

the top people in my school said
Q 7)

the magnetic field is ALREADY perpendicular to the current carrying wire (ie: the B field is going into page, perpendicular to wire) hence, theda is always 90
so to say, that that 45 degree is useless and used to trick everyone.

please, post your comment. because i put C and i hope its C
but i think it is D :rofl:
lol if it is, everyone that posted their MC answers got atleast one wrong

edit:
except that guy below
V

 

[Pianpupodoel]

1. C) G is the same everywhere in the universe, but g is not.
2. B) Line B is tangential
3. D) Provides experimental support for relativity - most correct answer
4. B) projectiles undergo constant acceleration
5. D) 1:64 is found from Keplar's Law
6. A) the wire will rotate about the magnet, because thats what wires do.
7. D) 0.849 N (sqrt{2 x [(0.4)^2]} x 3 x 0.5 = 0.849 N)
8. A) as flux through the loop is at maximium at t=0, and zero at two points during the cycle (when the loop is vertical and no magnetic flux goes through the loop)
9. C) flowing from X to Y as eddy currents are induced that oppose the motion (not sure about this)
10. A) this graph best depicts the situation, where a direct current flows through coil X, and only causes cutting of flux (and thus current/voltage in coil Y) when the current in X is switched on or off
11. A) Diffraction, check textbooks
12. C) Parallel to magnetic field does not affect magnetic force on a charged particle (use right hand palm rule)
13. D) decreases because of reduced metal lattice vibrations
14. C) as the only other option, perspex, does not conduct electricity
15. A) derived from calculations and reading from the graph

 

[RingerINC]

Here's mine and im pretty sure all of them are right except for like 2.
1. c
2. b
3. d
4. b
5. d
6. a
7. d
8. b
9. b -- i think this is wrong -- actually it might be right, if you got jacaranda check page 128 on em braking.
10. a
11. a
12. c
13. d
14. c
15. a

 

[alsha89]

my answers are as follows:
1. C
2. B
3. D
4. B
5. D
6. C
7. C
8. B
9. D
10. D
11. A
12. C
13. C - this was a mistake, i didn't read the graph headings properly and would now say it was D.
14. C
15. B

i feel pretty confident with most of them...

 

[Stopsign]

Looking at all your answers, I can conclude that I got about 12-13/15 (minimum)

How do you know whether we're right or wrong?

 

[Gecko888]

Question 9:

google 'Faraday disk dynamo'

you will get contradictory results! I think the Nasa site says B, one of the physics sites says C.

Otherwise my answers are exactly the same as pianpudodoel's.

 

[Stopsign]

I thought that 10 was D. It's a transformer so AC is used. It varies sinesoidally.

 

[Tbomb2k]

the top people in my school said
Q 7)

the magnetic field is ALREADY perpendicular to the current carrying wire (ie: the B field is going into page, perpendicular to wire) hence, theda is always 90
so to say, that that 45 degree is useless and used to trick everyone.

please, post your comment. because i put C and i hope its C
but i think it is D :rofl:
lol if it is, everyone that posted their MC answers got atleast one wrong

edit:
except that guy below
V

Yes you are totally right. that is what i did and it is D. the 45 deg tricks u. i was getting anoyed that every1 in this forum were saying C. it is sin90!! so it's D!

 

[RingerINC]

Question 9:

google 'Faraday disk dynamo'

you will get contradictory results! I think the Nasa site says B, one of the physics sites says C.

Otherwise my answers are exactly the same as pianpudodoel's.

i think some are electron flow and some are conventional current.

 

[danio33]

1 - c
2 - d - fucking stupidest fucking mistake ever argh!
3 - d
4 - b
5 - d
6 - a
7 - d
8 - b
9 - b
10 - a
11 - a
12 - c
13 - d
14 - c
15 - a

otherwise Im pretty confident with my answers. This years multiple choice seemed harder