No one today is not surprising that by touching the key switch, we can see the fire on the light bulb.Often we do not even think that all these actions are based on a series of physical phenomena.One of them is very interesting phenomena - the electrical conductivity of metals, which provides a flow of electric current.
For a start, perhaps, should decide what it all about.Thus, electrical conductivity is the ability of a substance to pass an electric current.Moreover, different materials have this ability to varying degrees.By the degree of conductivity substances are divided into conductors, semiconductors and insulators.
If you look at the experimental data obtained by researchers for the study of electric current, it becomes clear that the conductivity of metals is the highest.It also confirms the daily practice, when the transmission of electric current using metal wires.That metals primarily act conductors of electric current.And the explanation for this can be found in the electron theory of metals.
According to the last, the conductor is a lattice whose nodes atoms occupy.They are very tight and relate to such neighboring atoms, so are almost lattice sites.What can be said about electrons located in the outer shells of atoms.These electrons are free to move randomly, forming a so-called "electron gas".Here the electronic conductivity of metals and based on these electrons.
as evidence that the nature of the electric current due to the electrons, we can recall the experience of the German physicist Rikke, delivered in 1901.He took two copper and one aluminum cylinder with a carefully polished ends, placed one upon the other, and they passed through an electric current.According to the idea of the experimenter when the electrical conductivity of metals is caused by atoms, then came to the transfer agent.However, after passing an electric current within the cylinder, the weight has not changed.
This result followed the conclusion that the electric conductivity of metals caused by some particles inherent in all the conductors.In this role just came electron, which by this time had already been opened.In the future, we conducted several ingenious experiments, and they all confirmed that an electric current is caused by the movement of electrons.
In accordance with modern concepts of the crystal lattice of metals in its sites are located ions and electrons move relatively freely between them.That is a large number of electrons and provides high electrical conductivity of metals.If there is a small potential difference across the ends of the conductor, these free electrons begin to move, which causes an electrical current.
Here it should be noted that the conductivity is strongly temperature dependent.Thus, with increasing temperature the conductivity of metals is reduced, and conversely, increases as temperature decreases, until the phenomenon of superconductivity.At the same time it should be remembered that although the conductivity have all metals, its value for each of them its own.The best conductivity of the most widely used in the electrical and metal copper has.
So, given the material gives the notion of what constitutes the electrical conductivity of metals, explains the nature of electric current, and explains what caused it.The description of the crystal lattice of metals and the influence of some external factors on conductivity.
