$A$ wire of length $5\,m$ and radius $1\,mm$ has a resistance of $1\,\Omega$. What length of the wire of the same material at the same temperature and of radius $2\,mm$ will also have a resistance of $1\,\Omega$?

$A$ wire of resistance $3 \Omega$ is stretched to twice its original length. The resistance of the new wire will be (in $\Omega$)

Resistance of the wire is measured as $2\,\Omega$ and $3\,\Omega$ at $10^{\circ}C$ and $30^{\circ}C$ respectively. The temperature coefficient of resistance of the material of the wire is............$^{\circ}C^{-1}$.

Wires $A$ and $B$ have resistivities $\rho_A$ and $\rho_B$,where $\rho_B = 2 \rho_A$,and have lengths $l_A$ and $l_B$. If the diameter of wire $B$ is twice that of $A$ and the two wires have the same resistance,then the ratio $\frac{l_B}{l_A}$ is:

$A$ wire $50\, cm$ long and $1\, mm^2$ in cross-section carries a current of $4\, A$ when connected to a $2\, V$ battery. The resistivity of the wire is:

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the