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

Which of the following graphs represents the variation of resistivity ( $\rho$ ) with temperature $(T)$ for copper?

What is conductance? Write its unit.

Resistance of a wire at $0^{\circ} C, 100^{\circ} C$ and $t^{\circ} C$ is found to be $10 \Omega, 10.2 \Omega$ and $10.95 \Omega$ respectively. The temperature $t$ in Kelvin scale is $\qquad$

$A$ wire of radius $r$ has resistance $R$. If it is stretched to a radius of $\frac{3r}{4}$,its resistance becomes

Why does the resistance of metallic conductors and semiconductors change differently with a change in temperature?