Many people, even those who are far from the issues of physics, electrical engineering, electronics, have heard of such a term as "resistance", or a newer word - resistor. However, few people know what it is and what it is used for. So what is a resistor?
This question is easy to answer. Resistor is one of the most common electrical elements in radio engineering, TV-video-audio engineering. The main characteristic of resistors is their 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 rather expensive devices that are used in high-frequency ultra-precise equipment. Basically, they use general purpose resistors.
The resistance of general purpose resistors can vary by approximately +/- 10%. The resistance depends on the so-called temperature coefficient of resistance (in the specialized literature you can find the abbreviation TCR). Most standard resistors have a positive coefficient. This means that atas the temperature increases, so does the resistance.
What is a resistor in terms of its characteristics? One of the fundamental characteristics of resistors can be called power dissipation. This is the amount of power he can dissipate without taking damage. Power, as you know, is measured in such units 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 ^ 2R, where P is the power, I is the value of the current, R is the nominal resistance of the resistor. From this we can conclude what a resistor is from the point of view of electrical engineering. This is the main structural element of any electrical circuit, the main function of which is to provide a nominal (known) resistance to the flow of electric current through this circuit in order to regulate voltage and current. For the purpose of regulating the voltage in a 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 voltage stability. The resistor for the LED is also arranged on similar principles. So that the LED does not actually immediately burn out from the currents passing through it, a current-quenching resistor is connected to it in series.
The resistance of a resistor depends on the material it is made of. It also depends on the cut area.(the larger the cut area, the lower the resistance), on the length of the resistor (the longer it is, the greater the resistance, respectively).
Resistors are conveniently marked by color or by numbers. With the help of such marking, you can find out the most important property of any resistor, namely the value of its resistance. You can find out what this or that color or number means in the device passport or from the manufacturer or supplier (for example, on the website).
