The hands of a clock are a physical indicator.
Indicator is something that indicates or serves to indicate . This verb, for its part, refers to meaning or showing something with signs or indications.
For example: “The success of a television character of this kind is an indicator of the country's cultural decline” , “The government is satisfied with the economic indicator that the International Monetary Fund has just released” , “The arrival of thousands of tourists to the city during the last weekend is an indicator that anticipates a great summer season.”
Indicator as representation
Indicators or indices are also used in economics , demography and sociology . This concept refers to the representation of a reality in a quantitative way.
The Big Mac Index , to mention one case, is an indicator that allows comparing the purchasing power of populations where the McDonald's chain sells its Big Mac hamburger. What is done is convert the price of the Big Mac to the dollar and compare it in different countries to find out if the purchasing power of consumers is high or low.
The Big Mac Index is an economic indicator used to compare purchasing power in different countries.
pH measurement
In the field of chemistry , an indicator is known as the substance that, when added to a sample, produces some chemical change that is noticeable to the naked eye. A clear example is the pH indicator .
The substance used to measure the pH of a medium is known as a pH indicator (an index that shows the degree of alkalinity or acidity of a solution; if its value is between 0 and 7, it is a solution. acidic, while between 7 and 14, of a basic one).
Generally, the pH indicator is used for chemical substances whose color changes with the pH, which is related to a modification in its structure that is induced by protonation (the addition of a proton to a molecule, a ion or an atom) or deprotonation (a molecule gives up a hydrogen cation) of the species.
An acid-base indicator has a change interval of one unit above and one below pH, during which it changes the color of the solution in which it is found, or colors it (if it is colorless). Some of the most used are methyl orange , which changes between pH 3.1 and pH 4.4, going from red to orange, and phenolphthalein, whose change range goes from pH 8 to pH 10, turning pink or colorless solutions violet.
Litmus paper, on the other hand, is a cheaper but less accurate method, and is classified as semiquantitative, meaning that it returns an approximate result of the pH of a given solution.
There are also homemade alternatives; For example, if you boil water with red cabbage (also called red cabbage), turmeric roots (which allow you to obtain curcumin), red rose petals, plum skin or purple cabbage (these last two are used by certain indigenous cultures). .
Every pH indicator has a protonation constant , which shows the displacement of the protonation reaction from its basic form. The color change can be seen if the concentration of the basic or acid form is greater than or equal to 10 times that of the opposite.
Other uses of the term indicator
An indicator can be a physical instrument that indicates something. In this sense, an arrow within a graphic scheme, a traffic sign that warns about the end of a road or the hand of a clock are indicators.
For everyday language, finally, indicators are signs that reflect some reality: “That the team has been eliminated from the tournament so soon is an indicator of how bad things are being done.”