impedance and admittance

Impedance (Z)

                       - of a circuit is the ratio of the phasor voltage v to the phasor current I, measured in ohms                                 (Ω).

Admittance (Y)

                       - is the reciprocal of impedance, measured in Siemens (S).

Impedances and Admittances of passive elements and Voltage relationships.

Element	Impedance	Admittance	Time domain	Frequency Domain
R	Z = R	Y = 1/R	v=Ri	V= RI
L	Z = jωL	Y= 1/(jωL)	v= L (di/dt)	V=jωLI
C	Z= 1/(jωC)	Y= jωC	v= C (dv/dt)	V=I/(jωC)

This table contains the important parameters in solving our circuits for this entire topic.

                         The impedance and admittance that were introduced to us, which means that in AC circuit we no longer computing only for the resistance but  the admittance of the circuit which is comprise of the resistance at the real value and then reactance at the imaginary value. And remember that a reactance is composed of both the positive reactance and inductive reactance that means the circuit has a capacitor involved and inductance there is an inductor involved.