Excess pressure on the concave side of the meniscus

In summary, the shape of the meniscus is determined by two forces: adhesion to the container and cohesion of water. These forces balance each other out to create the curved surface. The grip on the sides of a thin tube overcomes gravity and pulls the water upwards, leading to the curved meniscus. However, there are still some complexities and uncertainties surrounding the exact mechanism of this process.
  • #1
Joel Jacon
11
0
Why is there excess pressure always on the concave side or surface of the meniscus?

In my book it is also written that excess pressure balance the vertical resultant forces due to surface tension.
How can a pressure balance a force?

My teacher said that shape of meniscus does not depend on vertical component of force.
Which force is she talking about? Why doesn't the shape of meniscus does not depend on vertical force as there are also curved meniscus so shouldn't vertical force should have some role to play in the curved surface?
 
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  • #2
There are two forces involved in capillary action which dictate the curvature of the meniscus.
1. The adhesion of the molecules to the surface of the container - so water adheres to glass which drags the sides of the meniscus upwards
2. The cohesion of water which glues the surface of the water together as in raindrops.
So the shape of the meniscus is the balance, basically, of these two forces.

Naturally if a tube is thin the grip on the sides of the tube pulling the water upwards overcomes the force caused by gravity and pulls the water upwards. There are a few models for this but interestingly none of them exactly predict experimental results.

There a few complexities which I have left out for the sake of brevity.
 
  • #3
Puma said:
There are two forces involved in capillary action which dictate the curvature of the meniscus.
1. The adhesion of the molecules to the surface of the container - so water adheres to glass which drags the sides of the meniscus upwards
2. The cohesion of water which glues the surface of the water together as in raindrops.
So the shape of the meniscus is the balance, basically, of these two forces.

Naturally if a tube is thin the grip on the sides of the tube pulling the water upwards overcomes the force caused by gravity and pulls the water upwards. There are a few models for this but interestingly none of them exactly predict experimental results.

There a few complexities which I have left out for the sake of brevity.

What about the shape of meniscus?
 

Related to Excess pressure on the concave side of the meniscus

1. What causes excess pressure on the concave side of the meniscus?

The excess pressure on the concave side of the meniscus is caused by the difference in surface tension between the liquid and the solid surface, known as the Laplace pressure. This pressure increases as the radius of curvature of the meniscus decreases.

2. How does excess pressure affect the meniscus?

Excess pressure on the concave side of the meniscus can cause the meniscus to bulge or deform, leading to a change in the shape of the liquid's surface. This can also affect the flow of the liquid and lead to instability in the meniscus.

3. Can excess pressure on the concave side of the meniscus be harmful?

In most cases, excess pressure on the concave side of the meniscus is not harmful. However, in certain situations, such as when the meniscus is under high pressure or in a confined space, it can cause damage to the surrounding structures or affect the accuracy of measurements.

4. How can excess pressure on the concave side of the meniscus be measured?

The excess pressure on the concave side of the meniscus can be measured using a variety of techniques, such as surface tension measurement devices, contact angle measurement, or through direct measurements using specialized equipment.

5. How can excess pressure on the concave side of the meniscus be reduced?

Excess pressure on the concave side of the meniscus can be reduced by increasing the radius of curvature of the meniscus, either by increasing the liquid volume or by using a larger container. It can also be reduced by reducing the surface tension of the liquid or by using a material with a lower surface energy for the solid surface.

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