In tuning, we vary the capacitance of a
capacitor in the tuning circuit such that the resonant frequency of the
circuit becomes nearly equal to the frequency of the radio signal received When this happens, the amplitude of the current with the frequency of
the signal of the particular radio station in the circuit is maximum It is important to note that resonance phenomenon is exhibited by a
circuit only if both L and C are present in the circuit Only then do the
voltages across L and C cancel each other (both being out of phase)
and the current amplitude is vm/R, the total source voltage appearing
across R