Is Area Intensive: Multiple Facts You Should Know


We know that the physical property of the system is categorized mainly into two types, intensive and extensive, based on the dependency on physical nature.

An intensive property does not depend on the substance’s amount, size, or shape. In contrast, an extensive property always confides in the system’s shape, size, and amount. The area is one of the physical entities; thus, let us study is area intensive property of the system or not.

Is area intensive?

The area is the two-dimensional representation of space occupied by an object on the surface. The surface may be curved or plane.

The area does not depend on the shape or size of the region where the object has been placed, but its shape, texture, and size are essential to describe the area of the object. Thus, the area is not an intensive property, but it is extensive.

Intensive nature does not require a quantity of the system to describe the property. While measuring the area of any object, you can observe that the object’s length, thickness, and width are used to find the area, which are the quantities used to describe the physical feature; thus, the area is not an intensive but an extensive property.

File:Projected area-hardness test.svg - Wikimedia Commons
Area occupied by an object on the surface
Image credits: Wikipedia commons
File:Sphere and circumscribed cylinder.svg - Wikimedia Commons, is area intensive
Area is extensive
Image credits: Wikimedia commons

When is the area extensive?

The extensive property is largely influenced by the external feature of the system rather than the internal behavior. The quantity of the matter is necessary to explain the physical property.

Measuring the area involves finding the length, breadth, height, or width of the object. Since all the quantities mentioned earlier are external appearance that depends on the size and shape of the object and are extensive; thus, the area is extensive.

Consider two rectangular slabs whose length is the same and breadth are different. If you measure their area, you will find the different values of the area because they have different breadth. This shows that the area is extensive.

How is the area extensive?

The extensive properties are always regarded as the additive of the subsystem, which means two or more physical dimensions are used to describe the single physical property. The area is one among them.

The area helps describe the physical existence of the object or system. Still, it does not involve identifying the system, which is one of the nature of the extensive property. The physical nature of the system changes with the size, shape, and amount of the substance, and the area is also varied with these entities.

For example, consider two objects one is rectangular, and the other one is triangular in shape. The region they take to occupy the surface is different from one another. And the way of measuring is also different. Thus the area is extensive.

Is change in area intensive?

Intensive property refers to whether there will be a change occurring in quantity; the physical feature will remain the same.

Suppose any change in the area occurs, and the shape and size of the system change by altering its length and breadth. So change in area is also not an intensive property, but it is extensive.

For example, consider a slab whose area is 6m2; if its area is changed to 5m2, it means that there will be a change in its size. It means that change in area is also extensive.

File:Same-volume-different-surface.svg - Wikimedia Commons
Change in Area is extensive
Image credits: Wikimedia commons

Is surface area intensive property?

Surface area refers to an open boundary of space occupied by the three-dimensional object. The surface area gives the sum of all the area occupied by each face of the object.

The intensive property of a physical system is the bulk property which cannot be computed. But by the above-mentioned formula, we can easily know that the surface area can be computed by knowing the length, width, and height. And it changes from one object to another depending on its size. Thus the surface area is extensive, not intensive.

The surface area of the liquid can be increased by applying energy due to intermolecular force and called surface tension. This property is intensive. So we can state that an extensive property can lead an object to gain intensive property.

File:Pentagonal Pyramid Surface Area.png - Wikimedia Commons
Three-dimensional Surface area of pentagon
Image credits: Wikimedia commons

Why is the area extensive?

The area can define the object’s physical appearance, but it cannot describe the nature and behavior of the object.

Area describes the region occupied by the object, but it cannot specify some properties such as density, gain, or temperature loss and cannot identify the object. And the area of the object varies with the size and configuration of the object. Thus the area is an extensive property of the matter.

How is surface tension intensive?

Surface tension is the bulk property exerted on the surface of the liquid due to intermolecular forces between the molecules.

The surface tension is due to an increase in the surface area of the liquid due to the exertion of some amount of energy. If some more amount of liquid is added, the energy to increase the surface area remains the same, and surface tension does not change; thus, it is intensive.

How can you explain intensive and extensive property in gas?

Gas has several properties such as pressure, internal energy, enthalpy, volume, temperature, entropy, etc.

Consider a gas in a container. Split the container into two halves and measure each property of the gas. If any property changes after splitting, then it is extensive. If there will be no change in any property, it is intensive.

  • After splitting, some of the properties like volume, internal energy, enthalpy, and entropy are reduced to half of their original value; thus, they are extensive.
  • Properties such as temperature, pressure, and density do not change even after splitting. Thus they are intensive.

Give any five examples for the extensive property?

The physical properties relatively proportional to the mass, shape, size, and configuration are called extensive; they are

  • Volume
  • Length
  • Internal energy
  • Specific heat capacity
  • Enthalpy
  • Amount of the substance

Density is intensive property why? explain.

The object’s density does not depend on the mass, size, or shape of the object, and it will remain constant even if the mass is altered.

The ratio of any two extensive properties gives an intensive property. Density is one quantity which is the ratio of two extensive properties of the matter, i.e., mass and volume. Thus it is intensive. If the mass changes, the volume is also changed by the same amount leading to the density remaining unaltered.

Summary

From this post we learnt that area is extensive property and is extremely influenced by the size and texture of the object. And area in three-dimensional space is also extensive.

Keerthi Murthi

I am Keerthi K Murthy, I have completed post graduation in Physics, with the specialization in the field of solid state physics. I have always consider physics as a fundamental subject which is connected to our daily life. Being a science student I enjoy exploring new things in physics. As a writer my goal is to reach the readers with the simplified manner through my articles. Reach me – keerthikmurthy24@gmail.com

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