The length of the wire is doubled. Its conductance will be

Choose the correct alternative:
$(a)$ Alloys of metals usually have (greater/less) resistivity than that of their constituent metals.
$(b)$ Alloys usually have much (lower/higher) temperature coefficients of resistance than pure metals.
$(c)$ The resistivity of the alloy manganin is nearly independent of/ increases rapidly with increase of temperature.
$(d)$ The resistivity of a typical insulator (e.g.,amber) is greater than that of a metal by a factor of the order of $(10^{22}/10^{23}).$

$A$ conductor has resistance values of $2.71 \ \Omega$ and $3.70 \ \Omega$ at $10^{\circ}C$ and $100^{\circ}C$ respectively. The temperature at which the resistance is $3.26 \ \Omega$ is .......... $^{\circ}C$.

$A$ resistance $R$ is stretched to four times its length. Its new resistance will be

The electric resistance of a certain wire of iron is $R$. If its length and radius are both doubled,then

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............$^{\circ}C^{-1}$.