Real-number conductance and imaginary-number susceptance combine to form complex admittance, symbolized by the capital letter Y. This is a complete expression of the extent to which a circuit allows ac to flow.
As the absolute value of complex impedance gets larger, the absolute value of complex admittance becomes smaller, in general. Huge impedances correspond to tiny admittances, and vice versa.
Admittances are written in complex form just like impedances. But you need to keep track of which quantity you’re talking about! This will be obvious if you use the symbol, such as Y = 3 βˆ’ j0.5 or Y = 7 + j3. When you see Y instead of Z, you know that negative j factors (such as in the quantity 3 βˆ’ j 0.5) mean there is a net inductance in the circuit, and positive j factors (such as in the quantity 7 + j3) mean there is net capacitance.
Admittance is the complex composite of conductance and susceptance. Thus, complex admittance values always take the form Y = G + jB. When the j factor is negative, a complex admittance may appear in the form Y = G βˆ’ jB.