In the last passage , we talked the relationship between the Resistance R, inductance L, and capacitance C , hereby we will discuss some more information about them .
As for why inductors and capacitors generate inductive and capacitive reactances in AC circuits, the essence lies in the changes in voltage and current, resulting in changes in energy.
For an inductor, when the current changes, its magnetic field also changes (energy changes). We all know that in electromagnetic induction, the induced magnetic field always hinders the change of the original magnetic field, so as the frequency increases, the effect of this obstruction becomes more obvious, which is the increase of inductance.
When the voltage of a capacitor changes, the amount of charge on the electrode plate also changes accordingly. Obviously, the faster the voltage changes, the faster and more the movement of the amount of charge on the electrode plate. The movement of the amount of charge is actually the current. Simply put, the faster the voltage changes, the greater the current flowing through the capacitor. This means that the capacitor itself has a smaller blocking effect on the current, which means that the capacitive reactance is decreasing.
In summary, the inductance of an inductor is directly proportional to frequency, while the capacitance of a capacitor is inversely proportional to frequency.
What are the differences between the power and resistance of inductors and capacitors?
Resistors consume energy in both DC and AC circuits, and the changes in voltage and current are always synchronized. For example, the following figure shows the voltage, current, and power curves of resistors in AC circuits. From the graph, it can be seen that the power of the resistor has always been greater than or equal to zero, and will not be less than zero, which means that the resistor has been absorbing electrical energy.
In AC circuits, the power consumed by resistors is called average power or active power, denoted by the capital letter P. The so-called active power only represents the energy consumption characteristics of the component. If a certain component has energy consumption, then the energy consumption is represented by the active power P to indicate the magnitude (or speed) of its energy consumption.
And capacitors and inductors do not consume energy, they only store and release energy. Among them, inductors absorb electrical energy in the form of excitation magnetic fields, which absorb and convert electrical energy into magnetic field energy, and then release magnetic field energy into electrical energy, continuously repeating; Similarly, capacitors absorb electrical energy and convert it into electric field energy, while releasing electric field energy and converting it into electrical energy.
Inductance and capacitance, the process of absorbing and releasing electrical energy, do not consume energy and clearly cannot be represented by active power. Based on this, physicists have defined a new name, which is reactive power, represented by the letters Q and Q.
Post time: Nov-21-2023