Obtain the condition at resonance draw a plot showing the variation of current with the frequency of a.c. source for two resistances and `R_(1)` and `R_(2)(R_(1) gt R_(2))`. Hence define the quality factor Q and write its role in the tuning of the circuit.

Explanation

At resonance, `I_(m)` is maximum
`rArr X_(L) = X_(C.)`
[Alternatively : `omega_(0) = (1)/(sqrt(LC))`]

Quality factor of LCR circuit is defined as `(omega_(0))/(2 Delta omega)`
`= (omega_(0)L)/(R )`
A largr value of quality factor corresponds to a sharper resonance.