السعة الكهربائية - الطاقة الكهربائية .. الفيزياء

Electrical Capacitance - Electrical Energy .. Physics

Electrical Capacitance

The charge is stored in the electrical circuit by a device called a capacitor, which consists of two parallel metal plates separated by an insulating body such as air or mica. If we connect the two plates to the end of a table, the first (i.e. the one connected to the positive end) acquires a positive charge, and the second a negative charge, and as a result, a difference in electrical potential is formed between them. The capacitor is characterized by its capacitance S, which is the ratio of the charge stored in it K to the potential difference between its two ends, and its value is usually related to the properties of the capacitor itself. In a capacitor with two parallel plates, it is equal to the result of dividing the area of ​​the plate by the separating distance multiplied by a fixed quantity called electrical transmittance. A unit called the farad is used to measure capacitance, which is the capacitance of a capacitor with a charge value of one coulomb and the value of the potential difference between its two plates is also one volt. The farad is a very large unit of measurement and is usually replaced by a smaller unit, which is the microfarad.

Electricity in general is the study of the movement of electric charges, while the science of static electricity (electrostatics) is limited to the study of their properties in a state of stagnation only, and the electric charge itself results from the presence of (negative charge) or the absence of (positive charge) electrons. Every material that strips some electrons from its atoms by friction, for example, acquires a positive charge. For example, if we rub a piece of glass

(resistors and capacitors connected in series and parallel)

with a silk cloth, this leads to the transfer of electrons from the glass, which becomes positive, to the silk, which becomes negative. Every body loaded with a positive charge is characterized by its ability to attract another body loaded with a negative charge. There is repulsion between bodies carrying the same type of charge. Coulomb's law allows for the calculation of the forces between charges, which are equal to the product of the two charges divided by the square of 15 25 the distance between them.

(Top image) Opposite charges are attracted to each other and like charges repel each other.

(Right) The charge generated by the belt's movement accumulates on the insulated metal ball in a Van de Graaff generator. The displacement of air molecules in the lower part of the generator then generates a charge on the belt itself, which in turn transfers it to the ball in its upper section.