Q26c (1 Viewer)

[haboozin]

Determine the sign and magnitude of the charge of the particle if its suspended motionless between the plates?

(diagram attached)


My trusty friend said its because this apparatus was vertically up so the charge has to be possitive since gravity pulls it down and the charge wants to go up.. (famous german guys oil drop experiment).

i've never heard or seen a question like this? and this question never said this appatus was suspended up in the air. It said "horisontal", so slack. did anyone write that answer for it? (or know of an answer which they think is correct)?

 

[fizzwizz]

yes - it wasn't a hard q. Positive charges repel , objects have weight - thats about it.

 

[haboozin]

yes - it wasn't a hard q. Positive charges repel , objects have weight - thats about it.

but how did u know that the setting was vertical...
i thought it was horisontal on the ground or something (well without the friction).

 

[kieraicos]

der haboozin!

omg der haboozin! lol did u think it was set up like literally as it was in the picture just coz it said 'horizontal' omg lol ur so silly! its always set up the other way! ive seen u in the 4 unit forum so why didnt u just use the maths way to do it! u messed up big time... there goes 3 marks :'( who else thinks this exam was SO easy?

 

[Captain Gh3y]

Not really, it was another poor question that required the students to make certain assumptions, and obviously not everyone sees the diagram the same way.

But yeah, the particle did end up being positivelyy charged to balance out gravity, in the same way as Miliken's oil drop experiment.

 

[fizzwizz]

youre right in a way but remember it said that the particle was charged and was suspended i.e. stationary Therefore it had no vertical motion, so weight must have been balanced by some force. In this case, only a anttractive force from "top" plate could provide this.

 

[TomT]

the question says that the plates were horizontal and since they are at 90 degrees to the apparatus, the apparatus must have been set up vertically.

 

[fizzwizz]

captain - i dont think it was a poor question - at least it had good physics. There is no other way except that it was in a vertical plane to interpret situation.

 

[haboozin]

Miliken's oil drop experiment

??

see i've never heard of that either...
is that like preliminary work or something?

this is sooo dodgy.. i read every part of the hsc syllabus (both sections) and never heard of the oil drop experiment?

 

[Captain Gh3y]

Miliken's oil drop experiment

??

see i've never heard of that either...
is that like preliminary work or something?

this is sooo dodgy.. i read every part of the hsc syllabus (both sections) and never heard of the oil drop experiment?

No, that experiment is not in the syllabus (yeah, it's in preliminary), but it's not about that experiment in any way; you could do the question without having heard of the experiment.

It was an application of E = V/d and F = qE from Ideas to Implementations and W = mg from Space.

 

[haboozin]

No, that experiment is not in the syllabus (yeah, it's in preliminary), but it's not about that experiment in any way; you could do the question without having heard of the experiment.

It was an application of E = V/d and F = qE from Ideas to Implementations and W = mg from Space.

thats not my concern, i know my forces and reaction forces very well (mechanics in maths) but my concern is the stupid diagram... they either should have had a clearer explination of how its actually setup or should have done like a 3d diagram.

and about the oil drop, what i ment was, maybe if i knew the experiment i would have thought of it being that way.

i just wrote it was neutral (something stupid like that)

 

[helper]

It said the plates were horizontal. For the plates to be horizontal, that diagram has to be vertical.

 

[haboozin]

It said the plates were horizontal. For the plates to be horizontal, that diagram has to be vertical.

why is that?

sorry for my ignorance, but i just don't understand why it has to be.

btw helper, have you done the multiple choice?
could u post your answers, thats the other thing i've become very concerned about.

This question and MC

 

[helper]

I don't have them here. There is one question in particular that I am interested in what they are after. There is a simple answer that is straight from the syllabus or a more correct answer that pushes the syllabus. I at the moment think it will be the second.

As I sent in a PM to someone else, I am trying to stay out of the discussions here as it is better for everyone to get their beefs off their chest and not worry about the exam. There is nothing you can do about it now.

For the question
In a), you were asked to draw the magnetic field between the metal plates. To do this the plate surfaces have to be facing each other. For the two plates to be facing each other and horizontal the diagram must be vertical.

 

[haboozin]

I don't have them here. There is one question in particular that I am interested in what they are after. There is a simple answer that is straight from the syllabus or a more correct answer that pushes the syllabus. I at the moment think it will be the second.

As I sent in a PM to someone else, I am trying to stay out of the discussions here as it is better for everyone to get their beefs off their chest and not worry about the exam. There is nothing you can do about it now.

For the question
In a), you were asked to draw the magnetic field between the metal plates. To do this the plate surfaces have to be facing each other. For the two plates to be facing each other and horizontal the diagram must be vertical.

do u want me to post the MC?
then u can post the answers...

also, the diagram could be horisontal and the plates also horisontal facing each other?
why couldnt they just say that the apparatus was vertically up?

 

[helper]

I have the MC answers at school, I will send them to you by PM tomorrow afternoon.

why couldnt they just say that the apparatus was vertically up?
To do what it has done to you. Or more likely think that you had been exposed to enough similar diagrams to this.

 

[ying123123]

so its postive charge
oyeah lucky guess for me

 

[shobadaynature]

No, that experiment is not in the syllabus (yeah, it's in preliminary), but it's not about that experiment in any way; you could do the question without having heard of the experiment.

It was an application of E = V/d and F = qE from Ideas to Implementations and W = mg from Space.

somehow I can up with the same questions to use as you but STILL can't figure out how to manipulate it to work.

then i took a lucky guess of a positive charge and a number.