87.Resonance in RLC circuit

In an electrical circuit, the condition that exists when the inductive reactance and the capacitive reactance are of equal magnitude, causing electrical energy to oscillate between the magnetic field of the inductor and the electric field of the capacitor. Note 1: Resonance occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor and the discharging capacitor provides an electric current that builds the magnetic field in the inductor, and the process is repeated.

RLC circuit comprises of Resistor(R), Inductor(L) and Capacitor(C)

For a series RLC circuit at certain frequency called resonant frequency, the following points must be remembered. So at resonance:

1. Inductive reactance X_L is equal to capacitive reactance X_C.
2. Total impedance of circuit becomes minimum which is equal to R i.e Z = R.
3. Circuit current becomes maximum as impedance reduces, I = V / R.
4. Voltage across inductor and capacitor cancels each other, so voltage across resistor V_r = V, supply voltage.
5. Since net reactance is zero, circuit becomes purely resistive circuit and hence the voltage and the current are in same phase, so the phase angle between them is zero.
6. Power factor is unity.