This circuit has a switch that controls the supply of current to an inductor. An inductor resists any changes in current. If you open the switch, the inductor tries to maintain the same current; it does this by charging the capacitance between the switch contacts. (There is some stray capacitance between any two wires in close proximity.) To simulate this, there is a small capacitor across the switch terminals (much larger than the actual value). When you open the switch, the voltage becomes very high; in real life this can cause a spark. From a physics course it is known that an inductor exhibits the phenomenon of self-induction. It consists in the fact that when the amount of current flowing through the coil changes, the magnetic field generated by this current also changes. This leads to a change in the magnetic flux through the coil. And, by the law of electromagnetic induction, a change in magnetic flux causes an EMF to appear in the circuit. By Lenz's rule, this EMF is directed so as to oppose the cause that generates it. In other words, when the current in an inductor changes, a certain EMF arises in it that opposes the change of this current. Self-induction Fig. 1. Self-induction. It turns out that the coil “resists” any changes in the current through it. If the current increases, it prevents it from increasing. If the current decreases, it prevents it from decreasing. For alternating current, which constantly changes its value according to a harmonic law, the coil “resists” constantly. Thus, for alternating current one can speak of a special, inductive, resistance of the coil (for direct current this resistance is zero). This resistance differs significantly from active (resistive) resistance. Whereas at an active resistance the work of the current is converted into heat, at the resistance of the coil, during the rise of the current, its work is converted into the energy of the magnetic field in the coil, and during the decline it is returned from the magnetic field into the energy of the current. The coil, as it were, “reacts” to a change of the current through it due to inductance. That is why such resistance is called reactive. See also inductive kickback blocking
This page is a utility for simulating индуктивная отдача (реактивное сопротивление катушки) online with specified initial values.
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