The unit of specific resistance is

In order to increase the resistance of a given wire of uniform cross-section to four times its value,a fraction of its length is stretched uniformly until the full length of the wire becomes $\frac{3}{2}$ times the original length. What is the value of this fraction?

$A$ cylindrical metal wire of length $l$ and cross-sectional area $S$ has resistance $R$,conductance $G$,conductivity $\sigma$,and resistivity $\rho$. Which one of the following expressions for $\sigma$ is valid?

The conductivity of a superconductor is

$A$ uniform wire of resistance $R$ is uniformly compressed along its length,until its radius becomes $n$ times the original radius. Now,the resistance of the wire becomes:

The resistance of a resistance wire is $5\,\Omega$ at $50\,^{\circ}\text{C}$ and $6\,\Omega$ at $100\,^{\circ}\text{C}$. The resistance at $0\,^{\circ}\text{C}$ will be ............. $\Omega$.