How Does Frequency Variation Affect RMS Current in an AC Circuit?

[alexmahone]

A coil, a capacitor and an AC source of RMS voltage 24 V are connected in series. By varying the frequency of the source, a maximun RMS current of 6 A is observed. If this coil is connected to a battery of emf 12 V and internal resistance 4 $\Omega$, the current through it will be
(a) 2.4 A
(b) 1.8 A
(c) 1.5 A
(d) 1.2 A

 

[Redbelly98]

You'll need to show your own attempt at solving this before receiving help. (Forum rules)

 

[alexmahone]

For maximum RMS current, the inductor and capacitor are at resonance; is that right?

 

[Redbelly98]

Yes.

 

[alexmahone]

Yes.

Thanks!