Resistance R, inductance L, and capacitance C are the three major components and parameters in a circuit, and all circuits cannot do without these three parameters (at least one of them). The reason why they are components and parameters is because R, L, and C represent a type of component, such as a resistive component, and on the other hand, they represent a number, such as a resistance value.
It should be specially stated here that there is a difference between the components in a circuit and the actual physical components. The so-called components in a circuit are actually just a model, which can represent a certain characteristic of the actual components. Simply put, we use a symbol to represent a certain characteristic of the actual equipment components, such as resistors, electric furnaces, etc Electric heating rods and other components can be represented in circuits using resistive components as their models.
But some devices cannot be represented by just one component, such as the winding of a motor, which is a coil. Obviously, it can be represented by inductance, but the winding also has a resistance value, so resistance should also be used to represent this resistance value. Therefore, when modeling a motor winding in a circuit, it should be represented by a series combination of inductance and resistance.
Resistance is the simplest and most familiar. According to Ohm’s law, resistance R=U/I, which means that resistance is equal to voltage divided by current. From the perspective of units, it is Ω=V/A, which means that ohms are equal to volts divided by amperes. In a circuit, resistance represents the blocking effect on the current. The larger the resistance, the stronger the blocking effect on the current… In short, resistance has nothing to say. Next, we will talk about inductance and capacitance.
In fact, inductance also represents the energy storage ability of inductance components, because the stronger the magnetic field, the greater the energy it has. Magnetic fields have energy, because in this way, magnetic fields can exert force on magnets in the magnetic field and do work on them.
What is the relationship between inductance, capacitance, and resistance?
Inductance, capacitance themselves have nothing to do with resistance, their units are completely different, but they are different in AC circuits.
In DC resistors, inductance is equivalent to a short circuit, while capacitance is equivalent to an open circuit (open circuit). But in AC circuits, both inductance and capacitance generate different resistance values with frequency changes. At this time, the resistance value is no longer called resistance, but is called reactance, represented by the letter X. The resistance value generated by inductance is called inductance XL, and the resistance value generated by capacitance is called capacitance XC.
Inductive reactance and capacitive reactance are similar to resistors, and their units are in ohms. Therefore, they also represent the blocking effect of inductance and capacitance on current in a circuit, but the resistance does not change with frequency, while inductive reactance and capacitive reactance change with frequency.
Post time: Nov-18-2023