Something about electric charge
Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field. There are two types of electric charges: positive and negative. Like charges repel and unlike attract. An object (one not made of antimatter) is negatively charged if it has an excess of electrons, and is otherwise positively charged or uncharged. The SI derived unit of electric charge is the coulomb (C). In electrical engineering, it is also common to use the ampere-hour (Ah), and, in chemistry, it is common to use the elementary charge (e) as a unit. The symbol Q often denotes charge. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that don't require consideration of quantum effects.
The electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces (See also: magnetic field).
Electric power - worth to know
Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.
Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes by the electric power industry through an electric power grid. Electric power is usually sold by the kilowatt hour (3.6 MJ) which is the product of power in kilowatts multiplied by running time in hours. Electric utilities measure power using an electricity meter, which keeps a running total of the electric energy delivered to a customer.
Electrical power provides a low entropy form of energy and can be converted into motion or other forms of energy with high efficiency
Suitable professionals on site
Especially in the case of large buildings electrical systems play a huge role. At the beginning should be designed and adequately equipping workers with the necessary wiring and mounting items. The installation itself mains also require supervision by a competent, highly qualified staff having qualified electrician. During the installation of electrical systems at the construction site should remain authorized persons, regardless of whether they plan to put electrical installations in the home or in a big high-rise. In each place is a risk that there is a dangerous situation is the same.