Question

The conductivity of a super conductor is:
A) Zero
B) Infinity
C) Depends on temperature
D) Depends on free electron

Answer 1

Hint: Superconductors are the conductors which are having its resistance value as zero and thus zero resistivity. As the resistance is zero efficiency will be a hundred percentage. Super conductivity can be achieved only in certain conditions

Complete step by step solution:
From free electron theory of metals we know that, when the temperature of a perfect metal decreased, the electron scattering of ions (or atoms) and thermal vibrations will also be decreased and hence the electrical resistance of the substance decreases.

That is, when the temperature is decreased to zero Kelvin temperature, the resistivity may reduce to zero. Based on this principle, many experiments were conducted on many substances. In 1911, Kamerlingh Onnes found that the resistance of pure mercury disappears suddenly at$4.2K$. This temperature is known as pure mercury’s superconducting transition temperature.

We know most of the material possesses a normal condition of resistance on the temperature that is above the superconducting transition temperature, and it can be referred to as the normal state. When the temperature becomes below the superconducting transition temperature, the resistance of the material becomes zero and because of this, its conductivity reaches infinity.

This state of the material is known as a superconducting state. So, the superconducting transition temperature is defined as the temperature at which a material changes its conducting state from normal state to superconducting state and total disappearance of electrical resistance of the substances is called superconductivity. The materials which show this property of superconductivity are called the superconductors.

Final answer is option (B), Infinity.

Note: The state of superconductivity can’t be achieved in normal cases. Thus there will be always power loss in transmission of electricity through the normal conductors. In recent years, no materials with significantly higher critical temperatures have been found.