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
 
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  • #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.
 
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  • #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:
 
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1. How does inserting a thin conductive foil affect the current in a resistor?

Inserting a thin conductive foil into a resistor increases the current flow through the resistor. This is because the foil decreases the resistance of the resistor, allowing more electrons to pass through and increasing the current.

2. Will inserting a thin conductive foil into a resistor damage the resistor?

No, inserting a thin conductive foil into a resistor will not damage the resistor as long as the foil is inserted carefully and does not cause any physical damage to the resistor. However, it is important to note that altering the resistor in any way may void its warranty or affect its performance.

3. Is there a limit to how much the current can increase after inserting a thin conductive foil into a resistor?

Yes, there is a limit to how much the current can increase after inserting a thin conductive foil into a resistor. This limit is determined by the maximum current rating of the resistor. If the current exceeds this rating, it can cause the resistor to overheat and potentially fail.

4. Can inserting a thin conductive foil into a resistor affect the voltage across the resistor?

Yes, inserting a thin conductive foil into a resistor can affect the voltage across the resistor. This is because the foil decreases the resistance of the resistor, which in turn affects the voltage drop across the resistor according to Ohm's Law (V=IR).

5. What other factors should be considered when inserting a thin conductive foil into a resistor?

When inserting a thin conductive foil into a resistor, it is important to consider the material and thickness of the foil, as well as the type and rating of the resistor. It is also important to ensure that the foil is inserted securely and does not cause any damage to the resistor or surrounding components.

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