$A$ strip of copper and another of germanium are cooled from room temperature to $80\, K$. The resistance of

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 $(10^{22}/10^{23}).$

If the length of a wire is increased by $0.1\%$,what is the percentage increase in its resistance (in $\%$)?

$A$ wire of resistance $5 \Omega$ is stretched so that its new length is $3$ times its original length. What is the resistance of the new wire?

The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be..... $\%$.

What length of the wire of specific resistance $48 \times 10^{-8} \, \Omega \, m$ is needed to make a resistance of $4.2 \, \Omega$ (in $.1$)? (Diameter of wire = $0.4 \, mm$)