Admittance (Y) is the reciprocal of the impedance of a circuit. Admittance of an AC circuit is analogous to the conductance of a DC circuit. The unit of Admittance is Simen or MHO
Admittance = 1/Z simen
Y = Conductance ± J Susceptance
Or the Admittance can be written as
Y = (G ± J B) Simen
Now comparing the above equation by the given equation in the question i.e Y= a + jb
∴ a = G = Conductance
EXAMIANS