Uncharged object between two charged plates

  • #1
416
51

Homework Statement


Imagine if you have two charged plates which have the same magnitude but opposite in charges.
If you place an uncharged object near of the positive plate what will happen?

Homework Equations


I don't think it depends on equations

The Attempt at a Solution


Okay, so If you rub a balloon with your hair, it will gain a negative charge. If you place that balloon really close to really small pieces of paper, It will attract them because the balloon will repel the electrons away from it and the protons don't move so the object will be polarized ( I am pretty sure that I cant say that this effect split the electrons and protons into two different sides equally , can I?)
So the negative charge will attract the protons more than it will attract the electrons because the protons are much closer to it than the electrons. So that will result in a net force to the balloon.

Now back to the question
If I place the uncharged object near the positive plate, the opposite of the above will happen. However, The negative charged plate will attract the protons and the positive plate will repel the protons in the same direction
and the same thing will happen to the electrons but opposite.

The answer in my book was that the uncharged object wont move. But what I think if we assume that it wont move we are just saying that the (distance) between the repelled electrons and attracted protons is just zero which proves that the first idea is wrong.


So, What is really happening here?

Thanks in advance.
-Biker
 
Last edited:

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2020 Award
35,536
6,431
There's a difference between the field from a charged sphere and the field between parallel plates. As you say, the electrons in the object will be attracted towards the positive plate, but what does that mean regarding the interaction with the negative plate?
 
  • #3
416
51
There's a difference between the field from a charged sphere and the field between parallel plates. As you say, the electrons in the object will be attracted towards the positive plate, but what does that mean regarding the interaction with the negative plate?
Sorry, I didn't get your question. Could you explain what you mean?

The positive plate will attract electrons and the negative plate will repel electrons, But also I have to take into account that the positive plate will repel protons and the negative plate will also attract protons. If that is what you mean

The force of the negative plate will be weaker (because it increases the distance) than the force of the positive plate but they are in the same direction
 
Last edited:
  • #4
ehild
Homework Helper
15,543
1,909
The force of the negative plate will be weaker (because it increases the distance) than the force of the positive plate but they are in the same direction
If the plates are parallel and close to each other, the electric field is homogeneous between them.
 
  • Like
Likes Biker

Related Threads on Uncharged object between two charged plates

Replies
2
Views
920
Replies
3
Views
3K
Replies
1
Views
4K
Replies
2
Views
8K
Replies
1
Views
2K
Replies
6
Views
3K
Replies
5
Views
13K
Replies
1
Views
695
Replies
5
Views
589
Replies
9
Views
3K
Top