Many people, even those far from the questions of physics, electrical engineering, electronics, have heard of such a term as “resistance”, or a newer word - a resistor. However, 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 is one of the most common electrical elements in radio engineering, television and video audio equipment. The main characteristic of resistors is its resistance, which is measured in Ohm units. 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 ultra-precise equipment. Basically, they use general-purpose resistors.
The resistance of general purpose resistors can vary approximately within +/- 10%. Resistance depends on the so-called temperature coefficient of resistance (in the specialized literature you can find a reduction in TCS). Most standard resistors have a positive coefficient. This means that with increasing temperature, the resistance also increases.
What is a resistor in terms of its characteristics? One of the fundamental characteristics of resistors is power dissipation. This is the power that he can dissipate without getting damaged. Power is known to be measured in units such as watts. Knowing the nominal resistance and current flowing through an electric circuit, power can also be calculated. It is found by the formula P = I ^ 2 * R, where P is the power, I is the current value, 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 electric circuit, the main function of which 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 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 excessive voltage, thereby equalizing individual currents in the branches of the electric circuit and maintaining voltage stability. A 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 suppressor is connected to it in series.
The resistance of the resistor depends on the material of which it consists. It also depends on the area of the cut (the larger the area of the cut, the lower the resistance), the length of the resistor (the longer it is, the higher the resistance, respectively).
Resistors are conveniently color-coded or numbered. With the help of such markings, you can find out the most important property of any resistor, namely the value of its resistance. You can find out what a particular color or number means in the device passport or from the manufacturer or supplier (for example, on the website).