An *LC circuit* consists of two components: a [[Capacitor|capacitor]] and an [[Inductor|inductor]. ![[lc_circuit.exalidraw.light.svg]] The two plates are a [[capacitor]] and the twisted line represents the coil/[[inductor]]. When the two are connected together, they function like a pendulum for electrons. The two plates of the capacitor are connected to each other via the coil. So that we can see an oscillation, we start with positive charges on the upper plate of the capacitor and negative charges on the lower one. To illustrate the oscillation, we can use a mechanical pendulum as an analogy: A stone on a rope oscillates in the same way as the electrons in the oscillating circuit. ![[lc_circuit_pendulum.excalidraw.light.svg]] If no current flows, this corresponds to a deflected pendulum. Nothing moves, but that changes as soon as we let go of the stone or close the circuit. As soon as the circuit is closed, a current flows from the upper to the lower plate. In the image of the mechanical pendulum: The stone begins to fall. The change in current creates a magnetic field in the coil. This initially counteracts the current. It therefore builds up more slowly than it would otherwise. However, the effect also counteracts the current's decay. This means that more charges are transported to the other plate of the capacitor than just to balance the charge. Now there are more positive charges on the lower plate and an excess of negative charges on the upper one. This inertia that the coil adds to the oscillating circuit corresponds to the inertia of the stone. The stone does not stop at the lowest point, but is driven further and rises again on the other side. From there, the process starts again, but in the opposite direction. The current flows or the stone swings back: an oscillation occurs. The coil and capacitor therefore form what is known as an oscillating circuit. A form of [[Harmonic Oscillator|harmonic oscillator]] for electric currents. >[!read]- Further Reading >- [[Electromagnetism]] >- [[Capacitor]] >- [[Inductor]] >[!ref]- References