värähtelypiiri

Värähtelypiiri, also known as a resonant circuit or tuned circuit, is an electrical circuit that can oscillate at some specific frequencies. These frequencies are determined by the circuit's components, typically an inductor (L) and a capacitor (C). The fundamental principle behind a värähtelypiiri is the exchange of energy between the inductor's magnetic field and the capacitor's electric field.

When a voltage is applied, the capacitor charges, storing energy in its electric field. As the capacitor discharges, it allows current to flow through the inductor, building up a magnetic field and storing energy there. This magnetic field then collapses, inducing a voltage that recharges the capacitor, but in the opposite direction. This process repeats, causing the circuit to oscillate.

The natural resonant frequency (f0) of an ideal LC värähtelypiiri is given by the formula f0 = 1 / (2 * pi * sqrt(LC)), where L is the inductance in henries and C is the capacitance in farads. In real circuits, resistance (R) is always present, which causes the oscillations to decay over time, a phenomenon known as damping. Circuits with significant resistance are often referred to as damped RLC circuits.

Värähtelypiirit are fundamental components in many electronic applications. They are used in radio receivers and transmitters to select or generate specific frequencies, in oscillators to create stable AC signals, and in filters to pass or block certain frequency bands. The sharpness of the resonance, or how narrow the range of frequencies the circuit responds to, is determined by the quality factor (Q) of the circuit.