Question

The fact the conductance of some metals rises to infinity at some temperature below a few Kelvin is called
A. Thermal conductivity
B. Optical conductivity
C. Magnetic conductivity
D. Superconductivity

Answer 1

Hint:Conductance is inverse of resistance which means that for the conductance to be infinity, the resistance tends to zero. A material whose resistance is almost zero even on applying a minimum external potential difference are known as superconductors having a very high conductivity.

Formula used:
The formula of conductance is,
$\sigma = \dfrac{1}{R}$
where $\sigma $ is the conductance and $R$ is the resistance.

Complete step by step solution:
Conductance is the ratio of a conductor's current to potential difference, which measures how well a thing conducts electricity. This is the resistance' inverse, and it is expressed in siemens or mhos. Therefore, we can write;
$\sigma = \dfrac{1}{R}$
As resistance decreases, conductance increases.

Conductance measures how much current a substance can transport because resistance is the reverse of current flow. For instance, a substance with low resistance can also be very conductive. Specific conductance is another name for conductivity.

We know that in a material whose resistance is almost zero even on applying a minimum external potential difference having a very high conductivity are known as superconductors. In superconductors high currents flow at a minimum potential applied to it.

Hence, option D is the correct answer.

Note: A superconductor is a metal that, at very low temperatures, allows electricity to flow through it without encountering any resistance. Materials known as superconductors provide no resistance to electrical current.