

The tendency of a system to oscillate at a particular frequency is called the natural frequency of the system. If the system is driven by an external energy source, whose frequency is equal to the natural frequency of the system, then amplitude reaches maximum and this phenomenon is called resonance. At resonance frequency, ω = 1/√LC
The series resonance circuit consists of inductance L, capacitance C and resistance R connected in series as shown below:

The parallel resonance circuit consists of inductance L, capacitance C joined in parallel to the source of alternating emf c as shown below:

