When the capacitor is fully discharged, the current is maximum and all the energy resides in the inductor. Hence, the energy of the capacitor is equal to the energy of the inductor.
2Li2m=2CQ2m...(i)
where im is the maximum current and Qm is the maximum charge.
The given values are
Qm=2.7×10−6CL=75×10−3HC=1.2×10−6F
The maximum current is found from equation (i)
im=LC1Qm⇒im=75×10−3×1.2×10−62.7×10−6=9mA