# Admittance **The reciprocal of [[impedance]].** > [!infobox] Admittance > | | | |:------------------- | -------------:| | ***Symbol*** | $\mathbf{Y}$ | | ***SI unit*** | siemens, $\text{S}$ | | ***SI base units*** | $\text{kg}^{-1}\;\text{m}^{-2}\;\text{s}^{3}\;\text{A}^{2}$ | > [!NOTE] Admittance > The *admittance* of an electrical conductor is the measure of the ease at which current flows through it. Admittance is also the reciprocal of impedance and is thus also a [[complex number]]. $\mathbf{Y}=\frac{1}{\mathbf{Z}}=\frac{\mathbf{I}}{\mathbf{V}}$ Admittance is the result of the combined effect of *conductance*, $G$, and *susceptance*, $B$, both also measured in siemens, and is expressed as $\mathbf{Y}=G+jB$ ## Series combination The total admittance of a series of components is the reciprocal of the sum of the reciprocals of their admittances. $\mathbf{Y}_\text{eq}=\frac{1}{\frac{1}{\mathbf{Y}_{1}}+\frac{1}{\mathbf{Y}_{2}}+\cdots+\frac{1}{\mathbf{Y}_{n}}}$ ![[AdmittanceSeries.svg|600]] ## Parallel combination The total admittance of parallel components is the sum of their individual admittances. $\mathbf{Y}_{\text{eq}}=\mathbf{Y}_{1}+\mathbf{Y}_{2}+\cdots+\mathbf{Y}_{n}$ ![[AdmittanceParallel.svg|600]]