Physical Properties of Matter (Physics)

If a hydrogen-inflated polythene balloon is released from the surface of the Earth, then the air pressure at high altitude is reduced. Thus, the balloon will expand until the pressure inside the balloon equals the pressure outside.

When some charge is placed on a soap bubble, the bubble will expand and its radius increases because the charge will distribute itself evenly over the surface of the bubble, and the repulsion between the same charges will cause it to expand until the surface tension can bring it to equilibrium. This will happen to both positive and negatively charged bubbles.

Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to external forces like gravity. Kerosene rises in the wick of the lamp through capillary action. If a person wants to consume the soft drink, he needs to impose some external force by his mouth.

As we know capillary action takes place only in the absence of any external force, hence one would not be able to use a straw. Blotting paper also works on the principle of capillary action.

It has a large number of pores on its surface which acts like a capillary tube. Nature is an excellent user of capillary action. The fine roots of trees act as capillary tubes, which provide them useful nutrients and water.

We can find several examples of capillarity in our daily life, such as blotting soft ink by blotting paper, rising of underground water, the spread of water drop on a cotton cloth, rising of kerosene in the wick of the lamp.

But capillarity is not the only reason for rising of water from the roots of a plant to its foliage, apart from this transpiration and cohesion is also responsible for this process.

Kerosene oil rising in the wick of the stove is due to the surface tension of oil. The wick of the lamp has many holes which act as capillaries. So kerosene keeps on rising in the capillaries.

In a capillary tube, liquid rises in proportion with its surface tension. The liquid which has more surface tension would gain more height.

When a air bubble at the bottom of the lake rises to the top, it will increase in size. The pressure of the trapped air in the bubble decreases due to decreasing vertical liquid depth.

The fountain pen leak at high altitudes. It is because of low air pressure. The ink inside the fountain pen has high pressure compared to the low atmospheric pressure outside at high altitude, so ink flows out of the pen.

Hydraulic brake, hydraulic press, hydraulic elevator all works on the principle of Pascal's law which states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure variations remain the same.