When learning the basics of electrical engineering at one stage considered certainly resonance currents and voltages.These phenomena are inherent in alternating current circuits and can be both undesirable, requiring them to account in the simulation of power and switching circuits as well as useful.

example, the resonance in the AC circuit is often used in radio: tuned oscillating circuit based on the resonance voltage, allowing several times to enhance a low-power radio signal, as by transformation "capacity-inductance" there is a growth of the current value of the voltage.

Said oscillating circuit - is the foundation for understanding how the current resonance and (or) stresses.It is a closed electrical circuit comprising connected in parallel with the capacitor (capacitance C) and the coil (inductance L).In them through the process of "pumping" energy of the capacitance of the electric field in the magnetic field there are self-extinguishing inductance (due to the presence of active component R) fluctuations of a certain frequency.

In resonant mode circuit resistance to the passage of current is only active component of R. There are current resonance and voltage resonance.Consider their features.

current resonance occurs in the circuit in parallel with the switched capacitor and the coil, which ratings are selected so that the current on the C and L is current.As a result, the current value in the circuit «CL» higher than the overall circuit.

principle works as follows: when the power supply is an accumulation of a charge capacitor (up to rated power).Then you can just turn off the power and close the circuit in the circuit to begin the process of discharge to the coil.The current passing through it generates a magnetic field and generates the self-induction electromotive force directed counter current.Maximum its value is reached at the time of the full discharge of the capacitor.Accordingly, this means that all the stored energy capacity transformed into a magnetic field inductor.However, due to the self-inductance of the coil motion of charged particles does not stop.

Since backflow from the capacitor is no more (he discharged), it starts to happen recharging, but with a different polarity.As a result, the entire field of the coil is converted to charge the capacitor and the process repeats.Because of the intrinsic activity is R occurs gradually fading fluctuations.Thus, the current resonance is performed.

voltage resonance occurs in a series connection of resistor R, a coil L and a capacitor C. An important feature is the fact that the supply voltage is lower than the capacitor and the coil (at each element separately), but equal current is maintained.Moreover, the voltage and current are in phase.The main condition for the emergence and maintenance of this process - the equality of inductive and capacitive reactance.Accordingly, the impedance is found to be active.

To determine the actual voltage across the coil and the capacitor used Ohm's law.If it is equal to the product of the coil current to the inductive reactance (U1 = IX1).Accordingly, the capacitor current must be multiplied by the capacitance (U2 = IX2).Since a series connection of elements is equal to the current, and for resonance X1 = X2 voltage across inductance and capacitance are equal.Hence, increasing the reactive components, can achieve a significant increase in voltage U1 and U2, while maintaining constant values of the EMF source.The main applications - radio technician.