Resonance in electrical circuits

Electrical Resonance

In electrical circuits resonance is a phenomenon when the voltage and current are in phase with is each other. That is, the phase angle between the voltage and the current is zero. In circuits with pure resistive elements doesn't have
any phase difference between the voltages and currents but in circuits having energy storage elements such as inductance and capacitance they will be out of phase with each other depending on the values of their reactance.

The reactance which forms the imaginary component of the impedance is a frequency dependent parameter. For example the inductive reactance X_L = ωL increases as the frequency ω increases where as the capacitive reactance X_C =1/ωC decreases with increase in frequency. Since the imaginary part is responsible for the phase shift between the voltage and current, the resonance will occur at a frequency called resonant frequency when imaginary parts of impedance or admittance cancel each other.