Entropy — mysterious physical quantity. It has several definitions given by different scientists at different times. The concept of entropy appears in a set of problems of physics and related to it disciplines. Therefore it is very important to know what is entropy and as to define it.

Frequency characterizes by itself cyclic processes of fluctuations or the movement on a circle. It is equal to the number of repetitions of process per unit of time. For its measurement learn the number of fluctuations which happened for some period. Sometimes it is measured in more difficult ways. If the period of repetitions is known, it can just be calculated.

Frequency – the physical quantity reflecting number of fluctuations in mechanical, electromagnetic or other process. Besides usual linear frequency, consider cyclic (angular) frequency at rotation of bodies. Finding of these sizes in various tasks is carried out with use of the known formulas, ratios of parameters of bodies and indicators of their movement.

Did you urgently need to weld paste, and you remembered that somewhere in a case there was a starch? But on shelves it was found - what to take several packages of white powder? It is possible to find out it in the chemical way. Substance, suitable for starch definition, for certain is in your house first-aid kit.