Why is meniscus of water concave

Consequently, you don't get that prestigious engineering job, where, 20 years later, you would have invented a new water-based chemical to allow rubber to grip better. Sadly, 10 years later, a mother and her adorable 4-year old daughter are leaving the ice cream store and the little girl, whose shoes don't have your un-invented coating, slips on a napkin and drops her ice cream cone. She cries at her loss The moral of this fictional tale is that it is important to read the measurement correctly, and yes, in the picture above, the true volume in the graduated cylinder is at the bottom of the water level— As this picture shows, a meniscus can go up or down.

It all depends on if the molecules of the liquid are more attracted to the outside material or to themselves. A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container.

This occurs with water and a glass tube. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the container, as with mercury and glass. A flat meniscus occurs with water in some types of plastic tubes; tubes made out of material that water does not stick to.

In any case, you get the true volume of the liquid by reading the center of the liquid in the tube, which will the lowest vertical point of the liquid. Looking at water, you might think that it's the most simple thing around. Pure water is practically colorless, odorless, and tasteless. But it's not at all simple and plain and it is vital for all life on Earth. Where there is water there is life, and where water is scarce, life has to struggle or just "throw in the towel.

Surface tension in water might be good at performing tricks, such as being able to float a paper clip on its surface, but surface tension performs many more duties that are vitally important to the environment and people. Find out all about surface tension and water here. Plants and trees couldn't thrive without capillary action.

Capillary action helps bring water up into the roots. With the help of adhesion and cohesion, water can work it's way all the way up to the branches and leaves.

Read on to learn more about how this movement of water takes place. Adhesion and cohesion are important water properties that affects how water works everywhere, from plant leaves to your own body. Just remember The meniscus of a liquid is the upward or downward curve seen at the top of a liquid in a container. The nature of curve whether upward convex or downward concave depends on the surface tension the liquid and its adhesion capacity to the wall of the container. A concave meniscus occurs when the molecules of liquid are strongly attracted to the container wall rather than to each other.

A convex meniscus appears when molecules of liquid are strongly attracted to each other rather than to the wall of container. Most liquids, including water, show a concave meniscus but a great example of a convex meniscus is liquid mercury in a glass container. It is to be noted that in some cases, the meniscus appears in a straight line instead of any curvature at all. For example, water in some plastic cylinders. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces such as gravity.

This effect can be seen in the drawing-up of liquids between the hairs of a paintbrush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquified carbon fiber , or in a cell. It occurs when the intermolecular attractive forces between the liquid and the solid surrounding surfaces adhesive forces are stronger than the cohesive forces within the liquid.

If the diameter of the tube is sufficiently small, then the combination of surface tension which is caused by cohesion within the liquid and adhesive forces between the liquid and container act together to lift the liquid. The height h of a liquid column is given by:. Notice that the height to which the liquid is lifted is inversely proportional to the radius of the tube, which explains why the phenomenon is more pronounced for smaller tubes.

Consider a water-filled glass tube with a radius of 2 cm 0. For these values, the height of the water column is 0. By comparison, for a 4 m diameter glass tube in the lab conditions given above radius 2 m, or 6.

For a 0. A common apparatus used to demonstrate capillary action is the capillary tube. When the lower end of a vertical glass tube is placed in a liquid, a concave meniscus forms. Adhesion forces between the fluid and the solid inner wall pull the liquid column up until there is a sufficient mass of liquid for gravitational forces to counteract these forces. The meniscus is the curve caused by surface tension in the upper surface of a liquid.