Sarjaresonanssikytkentää

Sarjaresonanssikytkentää, or series resonance circuit, is an electrical circuit where an inductor (L) and a capacitor (C) are connected in series with a voltage source. At a specific frequency, known as the resonant frequency, the inductive reactance (XL) of the inductor equals the capacitive reactance (XC) of the capacitor. This phenomenon causes the impedance of the circuit to reach a minimum, ideally becoming zero if resistance is neglected. Consequently, the current flowing through the circuit reaches a maximum at resonance.

The resonant frequency (f0) is determined by the values of the inductor and capacitor and can be calculated using the formula f0 = 1 / (2 * pi * sqrt(L * C)), where L is in henries and C is in farads. In a practical series resonant circuit, there is always some resistance (R) present, which prevents the impedance from becoming zero and the current from becoming infinitely large. This resistance limits the current and affects the sharpness of the resonance, a property described by the circuit's quality factor (Q).

Series resonance circuits have important applications in tuning and filtering. They are used in radio receivers to select specific frequencies, in oscillators to generate stable frequencies, and in power electronics for resonant converters. The ability to achieve maximum current at a specific frequency makes them valuable for frequency-selective applications. Conversely, they can also be used to block unwanted frequencies by operating them slightly off-resonance.