The core function of inductance is to store alternating current (storing electric energy in the form of a magnetic field), but it cannot store direct current (direct current can pass through the inductor coil without hindrance).
The core function of capacitance is to store direct current (storing electric energy directly on the capacitor plates), but it cannot store alternating current (alternating current can pass through the capacitor without hindrance).
The most primitive inductance was discovered by the British scientist Faraday in 1831.
Typical applications are various transformers, motors, etc.
Schematic diagram of Faraday coil (Faraday coil is a mutual inductance coil)
Another type of inductance is the self-inductance coil
In 1832, Henry, an American scientist, published a paper on the self-induction phenomenon. Due to Henry’s important contribution in the field of self-induction phenomenon, people call the unit of inductance Henry, abbreviated as Henry.
The self-induction phenomenon is a phenomenon that Henry accidentally discovered when he was doing an electromagnet experiment. In August 1829, when the school was on vacation, Henry was studying electromagnets. He found that the coil produced unexpected sparks when the power was disconnected. In the summer vacation of the following year, Henry continued to study experiments related to self-induction.
Finally, in 1832, a paper was published to conclude that in a coil with current, when the current changes, an induced electromotive force (voltage) will be generated to maintain the original current. So when the power supply of the coil is disconnected, the current instantly decreases, and the coil will generate a very high voltage, and then the sparks Henry saw will appear (high voltage can ionize the air and short-circuit to produce sparks).
Self-inductance coil
Faraday discovered the phenomenon of electromagnetic induction, the most core element of which is that the changing magnetic flux will generate induced electromotive force.
Stable direct current always moves in one direction. In a closed loop, its current does not change, so the current flowing through the coil does not change, and its magnetic flux will not change. If the magnetic flux does not change, no induced electromotive force will be generated, so direct current can easily pass through the inductor coil without obstruction.
In an AC circuit, the direction and magnitude of the current will change over time. When AC passes through the inductor coil, as the magnitude and direction of the current are changing, the magnetic flux around the inductor will also change continuously. The change in magnetic flux will cause the generation of electromotive force, and this electromotive force just hinders the passage of AC!
Of course, this obstacle does not prevent AC from passing 100%, but it increases the difficulty of AC passing (impedance increases). In the process of blocking AC passing, part of the electric energy is converted into the form of magnetic field and stored in the inductor. This is the principle of inductor storing electric energy
The principle of inductor storing and releasing electric energy is simple process:
When the coil current increases—causing the surrounding magnetic flux to change—magnetic flux changes—generating reverse induced electromotive force (storing electric energy)—blocking the current from increasing
When the coil current decreases—causing the surrounding magnetic flux to change—magnetic flux changes—generating the same direction induced electromotive force (releasing electric energy)—blocking the current from decreasing
In a word, the inductor is a conservative, always maintaining the original state! He hates change and takes action to prevent the change of current!
The inductor is like an AC water reservoir. When the current in the circuit is large, it stores part of it, and when the current is small, it releases it to supplement!
The article content comes from the Internet
Post time: Aug-27-2024