Is the Formula for Surface Tension Incorrect?

In summary: So, in summary, the conversation is about the increase in surface area of a soap film and how it is affected by the number of surfaces. The issue is whether the increase in surface area should be measured as lx or 2lx, with the conclusion being that the total surface area increases by 2lx, including both sides of the film.
  • #1
rajatgl16
54
0
In the image that I've attached with this thread you can see proof of serface energy+surface tension. This scaned image is from my school book. When I was going through this topic I wound that in this
increase in surface area = 2lx
which according to me isn't reasonable. I discussed about it mwith my teacher but I'm not satisfied with his answer.
According to me
increase in surface area should be = lx.
Please post your comments on this
 

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  • #2
The soap film has two sides. You need to count both, thus the factor of 2.
 
  • #3
my teacher gave me the same explanation. But the point is 2 sides of soap film is okay for surface tension. But this in no way associated with area.
 
  • #4
rajatgl16 said:
But this in no way associated with area.
Why do you think that? What do you think you're finding the area of?
 
  • #5
well i think increase in surface area is denoted by LL'M'M in figure
 
  • #6
rajatgl16 said:
well i think increase in surface area is denoted by LL'M'M in figure
Surface area of what?
 
  • #7
rectangular frame
 
  • #8
rajatgl16 said:
rectangular frame
Why would you care about the area of the rectangular frame? That's not a surface. (Remember that this is a physics issue, not just geometry.)
 
  • #9
Then you tell me what is this?
 
  • #10
rajatgl16 said:
Then you tell me what is this?
Your trying to find the surface area of the soap film. It has two sides.
 
  • #11
Now check this one. iN THIS for a liquid bubble which too have 2 sides increase in surface area is taken as 4pi*r^2 not 2*4pi*r^2
 

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  • #12
rajatgl16 said:
Now check this one. iN THIS for a liquid bubble which too have 2 sides increase in surface area is taken as 4pi*r^2 not 2*4pi*r^2
I see a factor of 2.
 
  • #13
I too can see. But Thats for surface tension according to me.
As you can see in figure this topic is part b). Actually part one is for liquid drop. In that surface tension is taken to b 'T'. But as for a liquid bubble there are to effective surfaces, surface tension comes out to b '2T'.
 
  • #14
rajatgl16 said:
I too can see. But Thats for surface tension according to me.
As you can see in figure this topic is part b). Actually part one is for liquid drop. In that surface tension is taken to b 'T'. But as for a liquid bubble there are to effective surfaces, surface tension comes out to b '2T'.
OK, so what's the issue?
 
  • #15
Issue is still same In my thread I've asked why increase in surface area is taken as 2lx instead of lx.
 
  • #16
rajatgl16 said:
Issue is still same In my thread I've asked why increase in surface area is taken as 2lx instead of lx.
I answered that (twice): There are two surfaces. You need the total change in area of the surface.
 
  • #17
i'm not getting what you mean.
 
  • #18
please elaborate how increase in surface area= 2lx. It simply makes no meaning that due to 2 surfaces total area becomes twice or 2lx
 
  • #19
rajatgl16 said:
please elaborate how increase in surface area= 2lx. It simply makes no meaning that due to 2 surfaces total area becomes twice or 2lx
I'm not sure what to say without repeating the same words over again. A soap film has two sides. You want the change in total surface area. Each side increases by lx, thus the total is twice that.
 
  • #20
can you mark that area it in figure?
 
  • #21
rajatgl16 said:
can you mark that area it in figure?
No. The figure only shows one side of the film.
 
  • #22
this wire system is 2dimensional or 3d? And sliding has occurred from LM to L'M' or reverse?
 
  • #23
Do you agree that the soap film has two sides? Yes or no.
 
  • #24
yes. And by it i mean that the wire system LM on both (left and right) side is coated with soap film.
 
  • #25
rajatgl16 said:
yes. And by it i mean that the wire system LM on both (left and right) side is coated with soap film.
Not sure what you mean by left and right, since the diagram shows only one side of the film. I'd call the two sides front (shown) and back (not shown).
 
  • #26
ok i got your this point, and my point of left and right is wrong. Now after this what?
 
  • #27
rajatgl16 said:
ok i got your this point, and my point of left and right is wrong. Now after this what?
As the area of the frame increases by lx, the total surface area of the film increases by 2lx, including both surfaces.
 

1. What is surface tension?

Surface tension is the force that causes the molecules on the surface of a liquid to be pulled together, creating a sort of “skin” on the surface.

2. Why would the formula for surface tension be incorrect?

The formula for surface tension is based on the assumption that liquids have a continuous, uniform surface. However, recent research has shown that at a molecular level, the surface of a liquid is actually jagged and irregular. This means that the formula does not accurately reflect the behavior of surface molecules.

3. How was the incorrect formula discovered?

Scientists have used advanced imaging techniques, such as atomic force microscopy, to observe the surface of liquids at a molecular level. Through these observations, they have found that the surface of liquids is not as smooth as previously thought, leading to the realization that the formula for surface tension is incorrect.

4. How does the incorrect formula impact scientific research and applications?

The incorrect formula for surface tension could have significant impacts on various fields of science and technology, such as fluid dynamics, materials science, and pharmaceuticals. It may also require the reevaluation and adjustment of certain experiments and processes that rely on accurate surface tension calculations.

5. What are scientists doing to address this issue?

Scientists are currently working on developing more accurate models and formulas for surface tension, taking into account the irregularities at the molecular level. They are also conducting further research to better understand the behavior of surface molecules and their impact on surface tension.

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