# What is a resistor - the main characteristics

Many people, even those far from questions of physics, electrical engineering, electronics, have heard of such a term as "resistance", or a newer word - a resistor. However, very few people know what it is and what it is used for. So what is a resistor?

It is not difficult to answer this question. Resistor - one of the most common electrical elements in radio engineering, tele-video and audio equipment. The main characteristic of resistors is its resistance, which is measured in units of Ohms. There are two main types of these devices: general purpose and so-called stable. What is a stable resistor? These are quite expensive devices that are used in high-frequency high-precision equipment. In general, they use general-purpose resistors.

Resistance of general-purpose resistors can vary approximately within +/- 10%. The resistance depends on the so-called temperature coefficient of resistance (in the specialized literature one can find a reduction in TCS). For most standard resistors, this factor is positive. This means that as the temperature increases, resistance increases.

What is a resistor in terms of its characteristics? One of the fundamental characteristics of resistors can be called dissipated power. This is the power that it can dissipate without getting damaged. Power, as is known, is measured in units such as Watts. Knowing the nominal resistance and the current flowing through the electrical circuit, you can calculate the power. It is found by the formula P = I ^ 2 * R, where P - power, I - the current value, R - the nominal resistance of the resistor. Hence, we can conclude that such a resistor in terms of electrical engineering. This is the main structural element of any electrical circuit whose main function is to provide nominal (known) resistance to the flow of electric current through this circuit in order to regulate voltage and current. For the purpose of voltage regulation in the circuit, a so-called ballast resistor is often used. What is a ballast resistor? This device is connected to the network and absorbs a certain amount of excess voltage, thereby equalizing the individual currents in the branches of the electrical circuit and maintaining the voltage stability. On similar principles, a resistor for the LED is arranged. In order for the LED not to burn out directly from the currents passing through it, a current-carrying resistor is connected in series.

Resistor resistance depends on the material from which it is composed. Also, it depends on the area of the cut (the larger the cut-off area, the lower the resistance), the length of the resistor (the longer it is, the corresponding, respectively, the resistance is greater).

Resistors are conveniently labeled by colors or by digital symbols. With the help of this marking, you can learn the most important property of any resistor, namely the value of its resistance. To find out what a particular color or figure means, it is possible in the device's passport or from the manufacturer or supplier (for example, on the website).