The conductivity of a superconductor is.......

Masses of three wires of copper are in the ratio $1:3:5$ and their lengths are in the ratio $5:3:1$. The ratio of their electrical resistances is:

The resistance of a platinum resistance thermometer at $0\,^oC$ is $5\,\Omega$ and at $100\,^oC$ is $5.75\,\Omega$. When the resistance is $5.15\,\Omega$,the unknown temperature is ............ $^oC$.

What is electrical resistance $(R)$? On which factors does the resistance value depend?

Two conductors are made of the same material and have the same length. Conductor $A$ is a solid wire of diameter $1 \ mm$. Conductor $B$ is a hollow tube of outer diameter $2 \ mm$ and inner diameter $1 \ mm$. Find the ratio of resistance $R_A$ to $R_B$.

$A$ metal wire of specific resistance $64 \times 10^{-6} \, \Omega \cdot \text{cm}$ and length $198 \, \text{cm}$ has a resistance of $7 \, \Omega$. The radius of the wire will be ............. $\text{cm}$.