Question

The reciprocal of resistance is conductance. If the unit of resistance is ohm, the unit of conductance will be:
(A) Ohm
(B) Volt
(C) Per ohm
(D) \[Ohm{\text{ }}metr{e^{ - 1}}\]

Answer 1

Hint To answer this question we should first write down the definition of conductance. From the definition we can find out the quantities that conductance develops a relation with. This will help us to find the unit of conductance, as required for the answer.

Complete step by step answer
Conductance is defined as the ability of a substance to let the electric current pass through the substance with respect to the applied voltage.
Conductance is often known as the reciprocal of resistance. Conductance is denoted as $\sigma $.
The formula of conductance is:
$\sigma = \dfrac{1}{R}$
The unit of resistance is ohm, which we all know.
Now since conductance is the reciprocal of resistance therefore the unit of conductance should be reciprocal of the unit of resistance.
So the unit of conductance is $oh{m^{ - 1}}$ or this is also known as per ohm.
Hence the reciprocal of resistance is conductance. If the unit of resistance is ohm, the unit of conductance will be per ohm.

So the correct answer is option C.

Note: We have mentioned the term resistance in the answer. For a better understanding we should be knowing the definition of this term. By resistance we mean the tendency of a substance to oppose the current flow in an electrical circuit.
About conductance we should know that since it is the reciprocal of the resistance, the formula can be given as current divided by voltage.
We should not be confused between resistance and conductance. Resistance gives us an idea about how much the resistor into consideration resists the current flow through it. On the other hand conductance is the property which tells us how much the resistor into consideration allows the current to pass through it.