If a conducting wire of length $L$ is uniformly stretched to double its length, then its conductivity becomes . . . . . . .

$A$ wire has a resistance of $10\, \Omega$. If its length is increased by $10\%$ by stretching,what will be the new resistance of the wire in $\Omega$?

$A$ tapered bar of length $L$ and end diameters $D_1$ and $D_2$ is made of a material of electrical resistivity $\rho$. The electrical resistance of the bar is

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 $R_B$.

Three copper wires of lengths and cross-sectional areas are $(l, A)$,$(2l, A/2)$,and $(l/2, 2A)$. Resistance is minimum in

The lead wires should have