Current change after inserting thin conductive foil into resistor

  • #1
student_man
4
1
Homework Statement
Given are two square parallel metal plates, with dimensions a×a whose distance between them is d where d≪a. The space between the plates is filled with a conductive liquid with resistivity p. The plates are connected to a constant voltage source U. How much will the current through the plates change when a conductive foil is inserted into the space between the plates and bent in the middle as shown in the figure? The current at any point between the plates flows in the direction perpendicular to the plane of the upper plate.
Relevant Equations
Circuit attached
I tried splitting it up into 4 individual resistors, adding them up (each side serially and then both sides with each other as parallel) and then using V=IR but it ended up being the same current as the original.
(The answer should end up being (9/8)* the original current)
Screenshot 2023-10-05 185408.png
 
Physics news on Phys.org
  • #2
student_man said:
Homework Statement: Given are two square parallel metal plates, with dimensions a×a whose distance between them is d where d≪a. The space between the plates is filled with a conductive liquid with resistivity p. The plates are connected to a constant voltage source U. How much will the current through the plates change when a conductive foil is inserted into the space between the plates and bent in the middle as shown in the figure? The current at any point between the plates flows in the direction perpendicular to the plane of the upper plate.
Relevant Equations: Circuit attached

I tried splitting it up into 4 individual resistors, adding them up (each side serially and then both sides with each other as parallel) and then using V=IR but it ended up being the same current as the original.
(The answer should end up being (9/8)* the original current)View attachment 333071
Welcome to PF.

Interesting problem! Can you show your math where you ended up getting the same overall current?
 
  • #3
berkeman said:
Welcome to PF.

Interesting problem! Can you show your math where you ended up getting the same overall current?
Here is my math
SmartSelect_20231005_194723_Samsung Notes.jpg

I hope it's understandable : )
 
  • #4
I believe you left out the horizontal short-circuiting wire between the for 4 resistors... :wink:
 
  • #5
berkeman said:
I believe you left out the horizontal short-circuiting wire between the for 4 resistors... :wink:
I'm not really sure how to take it into consideration in the equations😅
The only information I'm given about the piece of foil is that it's conductive.
 
  • #6
The foil is an equipotential. It is a zero ohms link across a bridge of four resistors. Solve parallel then series, not series the parallel.
 
  • Love
Likes student_man
  • #7
Baluncore said:
The foil is an equipotential. It is a zero ohms link across a bridge of four resistors. Solve parallel then series, not series the parallel.
Thank you! :biggrin:
 
  • Like
Likes berkeman

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
6
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
7
Views
794
  • Engineering and Comp Sci Homework Help
Replies
0
Views
581
  • Engineering and Comp Sci Homework Help
Replies
2
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
5K
Replies
3
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
9
Views
4K
  • Engineering and Comp Sci Homework Help
Replies
2
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
288
Back
Top