An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores electrical energy in a magnetic field when electric current flows through it.
Inductors are widely used in alternating current(AC) electronic equipment, particularly in radio equipment.
* This simulation only works while the mouse is pressed.
* This simulation is based on the actual circuit being operated(except the first circuit on the left). The power supply voltage is 3V, and the inductor is 330μH. The resistance for current regulation is 0Ω.
Slow light up circuit
At turn on the switch moment, a current starts to flows through the inductor. It is causing a magnetic field's change. At this moment, the inductor generates back EMF(Electromotive force) against the magnetic field's change. In other words, the inductor acts like a resistance to the current change. This resistance component is called 'inductive reactance.'
If the switch is pressed steadily, there is no further change in the magnetic field, so the inductor's resistance gradually disappears, leaving only the cable's role. So the LED lights up.
In general circuits, the time intervals during which the LEDs light up are very short. Therefore, it is almost impossible to observe the process of lighting. The simulation above assumes an ideal situation.
A circuit that lights up for only a short time when you turn on the switch
As soon as you close the switch, the inductor is like a huge resistor because of the EMF. Therefore, most of the current flow to the LEDs.
As time passes with the switch closed, the resistance component of the inductor decreases. So, most of the current flow through the inductor instead of the LED.
Note: This circuit is not stable. When the inductor's resistance component decreases, a quite strong current flows through the inductor, making heat.
A circuit that lights up for only a short time whenever open the switch
When the switch is closed, a magnetic field is formed around the inductor.
If you open the switch after a while, an EMF is made in the inductor against the magnetic field decrease. The LED lights up with this EMF.
Note: The connection direction of the LED is different from the previous one.