Question

what role does the concept of susceptance play in the calculation of admittance?

Answer 1

Susceptance (B) is the imaginary part of admittance, where the real part is conductance. That is, Susceptance is that component of admittance, which comes from passive devices like Inductors and capacitors. In purely resistive circuits, ie., the circuits in which there is no capacitance or inductance, the admittance will be equal to the resistance of the circuit.

But when capacitance or inductance is present in the circuit, the admittance also has a imaginary component, along with the real resistive component, which is called Susceptance.