Observations :
  • The current at the resonant point will be larger if the resistance is small compared to when it is large.

  • When the resultant reactance in the circuit is large there will be only a small current flowing.

Hence, for a Series RLC Circuit with small resistance, there is a larger change in current as the frequency varies compared to when the resistance is larger i.e. a smaller resistance is said to give a sharper tuning

More accurately, the ratio of L to R governs the sharpness of tuning.

Here R1 < R2 < R3