Question

The unit of susceptance is
(A) ohm
(B) ohm^-1
(C) ohm/cm
(D) ohm/m

Answer 1

Hint: Susceptance is the reciprocal of reactance and reactance is the imaginary part of Impedance, while the real part of impedance is resistance. Using this information, if you can write the unit of reactance, you can deduce the unit of susceptance.

Complete step by step solution:
As susceptance is the reciprocal of reactance, its unit will be inverse that of the reactance. And we know that the unit of reactance is ohm, hence the unit of susceptance is $oh{m}^{-1}$.
If one doesn’t remember the unit of reactance then we can use the fact that reactance is the imaginary part of impedance whose real part is resistance. That means that resistance can be added to impedance. Two physical quantities can only be added if they have the same unit, and since the unit of resistance is ohm, the unit of reactance should also be ohm.

Therefore, the correct answer to the question is option : B

Additional information:
Impedance too has the same unit as resistance or reactance.
Susceptance is the imaginary part of admittance, whose real part is conductance, which is inverse of resistance. So conductance, susceptance or Admittance, all have the same unit ohm^-1.
The more common unit of susceptance, admittance and conductance in siemens. So for a multiple correct answer question, siemens is also a possible answer.

Note: Before attempting to solve the problem, the student needs to be able to understand the formulas of Impedance and Admittance. One should also be aware of the terms reactance, resistance, conductance and susceptance. But should not confuse these terms with susceptibility which is a dimensionless quantity.
Alternatively, one can also deduce the unit of susceptance by considering that it is the imaginary part of admittance and admittance has real part conductance. Since unit of conductance is known to be ohm-1, the unit of susceptance will also be same