Question

Reciprocal of impedance is:
(A) Susceptance
(B) Conductance
(C) Admittance
(D) Transconductance

Answer 1

Hint In AC circuits, resistance is not the only factor that opposes the flow of current. Inductance and capacitance also play a great role in opposing the flow of current. The combination of resistance, and capacitance or the combination of inductance and resistance or the combination of all three in a circuit that causes a restriction to the flow of current is called impedance.

Complete step by step answer
When a circuit has a combination of an inductor, a resistor, and a capacitor the effective resistance of the circuit due to the combination of these three is called the impedance of the circuit. In an ac circuit, the resistance due to the capacitance is called the capacitive reactance and the resistance due to an inductor is called the inductive reactance.
The impedance of a circuit means the restriction to the flow of current. The reciprocal of impedance is called the admittance of the circuit.
Impedance means the effective opposition faced by the current through a circuit and admittance means how much current is allowed to flow through the circuit.

The answer is: Option (C): Admittance

Additional information
The unit of impedance is Ohm $\Omega$
We know that admittance is the reciprocal of impedance, hence the unit of admittance is mho, $\mho$.

Note
There is a possibility of confusion between susceptance, admittance, and conductance of the circuit. Though the meaning of all these is the same, they mean different things. The reciprocal of resistance is called conductance. Susceptance is the reciprocal of the inductance of the circuit or the capacitance of the circuit.