Question

Reciprocal of impedance is
A. Susceptance
B. Conductance
C. Admittance
D. Transconductance

Answer 1

When we talk about an AC circuit, along with resistance the capacitance and inductance of the circuit also oppose the flow of charges in the circuit. When a combination of resistance - inductance or resistance – capacitance or all three together is connected in the circuit, the opposition to the current in the circuit by this combination is called the impedance of the circuit.

Complete step by step answer:
Let us first understand what impedance is. Impedance is the term used for an AC circuit when the circuit consists of some resistance along with a capacitor or an inductor.
We know that a resistance opposes the flow of charges in the circuit. Or resistance avoids current in the circuit.

In an AC circuit, inductance and capacitance also oppose the flow of charges through them. The opposition by the inductance and capacitance is similar to resistance and is called the reactance of the capacitor or the reactance of the inductor.

When a combination of resistance - inductance or resistance – capacitance or all three together is connected in the circuit, the opposition to the current in the circuit by this combination is called the impedance of the circuit.

The reciprocal of the impedance is called admittance of the ac circuit.
Like the opposite if truth is false, the opposite of impedance is admittance.

Impedance tells us how much the circuit components are opposing the circuit whereas admittance tells us how much is the circuit is allowing the current to flow in the circuit.

Since impedance is a type of resistance, impedance has the unit of ohm or $\Omega$.
Since admittance is the reciprocal of impedance, its unit is mho or $\mho$.
Hence, the correct answer is option C.

Note:
(i)Do not confuse between conductance, susceptance and admittance of a circuit. They all have the same meaning but are different.
(ii)Conductance is the reciprocal of resistance.
(iii)Susceptance is the reciprocal of reactance offered by capacitance or inductance in an AC circuit.
)iv)Admittance is the reciprocal of impedance offered by a combination of resistance - inductance or resistance – capacitance or all three together.