We explain what density is and some characteristics of this property. In addition, other types of density exist.
What is density?
The term density comes from the field of physics and chemistry, in which it specifically refers to the relationship between the mass of a substance (or a body) and its volume It is therefore an intrinsic property, since it does not depend on the amount of substance considered.
Density, property that is usually expressed in kilograms per cubic meter (kg / m 3 ) or gram per cubic centimeter (g / cm 3 ), varies to a greater or lesser extent in function of pressure and temperature, and also with changes in state.
Typically, gases have a lower density than liquids because they have less cohesive particles, and these in turn less than solids. Although there are exceptions, usually increasing the temperature decreases density. The density defined above is the absolute density; The relative density is the density of a substance in relation to another, the apparent density is what characterizes porous materials, such as soil.
The density of water is 1 g / cm 3 ; that of lead, for example, is much higher: 11.35 g / cm 3 . It is precisely for this reason that in the colloquial language, especially among young people, the term dense (and even, lead ) is used to qualify a person heavy, heavy, or a complex, problematic situation, it is called dense (dense atmosphere, dense conversation, etc.).
- On the web: Density and some exercises solved.
Other types of density
- Population Density In the area of demography, an important concept is that of population density, which refers to the number of inhabitants per square kilometer. China and India are examples of countries with very high population density, while the Nordic countries and Oceania have low population density. Areas of high population density are often associated with housing problems, air pollution, insufficient public services infrastructure, among others.
- Optical density This physical parameter constitutes the absorption of an optical element at a given wavelength per unit distance. This data is used to assess cell content, smoke quality generated by different substances, laser power, filters, etc.
- Density of electrical current. It is the relationship that exists between the intensity of electric current that circulates through a conductor per unit of time and per unit of cross section.
- Density of magnetic flux. Also called "magnetic induction, " it is the magnetic flux that causes a moving electric charge for each unit of area normal to the direction of the flow.
- Bone mineral density. In the medical field, this measure refers to the amount of minerals per unit area. It is usually expressed in g / cm 2 and is established for certain bones specifically, such as the femur or lumbar spine. A low bone mineral density can trigger osteoporosis, a disease in which the bones are found with a very low proportion of minerals (mainly calcium), so they become too porous and therefore fragile and brittle, thus increasing the risk of people to suffer fractures.
More in: Density of matter.