When impedances are connected in parallel, the same voltage V is impressed across each impedance. The current in each element is: IL=V/ZL IR=V/ZR IC=V/ZC From Kirchoff’s current law I= IL + IR + IC = V/ZL + V/ZR + V/ZC  = V(1/ZL+1/ZR+1/ZC)=V(YL+YR+YC)=V*Y0