The resistor - one of the most important components of any electrical circuits. Its main objective is to show resistance to the current passing through it. At the same time it heats up a little.
Resistor and its characteristics
The resistor is called a passive component as current decreases after passing through it. The resistor role in schemes is huge: it provides a stable operating mode of intensifying cascades on transistors and allows to control values of tension in electrical circuits.
The resistor - a linear element as its volt-ampere characteristic (dependence of current on the enclosed tension) represents the straight line drawn from the beginning of coordinates. The tangent of an inclination of this line with abscissa axis is inversely proportional to resistance size.
Resistance - the main characteristic of the resistor. It is measured in ohms, kilohms, megaohms, etc. In fact, any element in an electrical circuit has resistance, and current, passing through it, decreases. However at the resistor it is the main function, as allocates it against the background of all other elements. It is manufactured of various materials on which the difference between actual resistance and what is written on the case depends. The fact is that these two sizes at real devices differ a little. The value of resistance is specified on the resistor. Not less important characteristic is the power disseminated on it - thermal energy which appears at the time of passing of electric current. If it is excessively big, the resistor can fail. It is similar to burn-out of a stopper in an electrical network of the apartment at connection of all devices at the same time. To avoid breakage of the resistor, on it, besides resistance size, specify also maximum permissible disseminated power. Resistors for different chains select, proceeding from these two parameters.
Marking of resistors
Modern resistors are quite small by the size therefore not always it turns out to specify completely that resistance which they can render. To read so tiny inscription it will be problematic. Apply special reductions to convenience. The letter corresponds to certain units of measure (R - Ohms, K - kilohms, M - megaohms, etc.). On the resistor will be to specify only three symbols enough. Resistors which release at the American plants are marked in a different way. The two first figures designate face value, and the third - the number of zero. For example, 150 is designated by 15 Ohms, and 363 - 36 kOhm. Recently the enterprises which are engaged in release of resistors refuse former ways of marking and pass to marking by means of color. It is simpler to put it in the conditions of completely automated production. A certain multiplier and degree of accuracy matches every color. Apply up to six color strips on the most exact resistors. The first two always designate resistance face value.