Copper and silicon are cooled from $300 \ K$ to $60 \ K$. The specific resistance:

$A$ silver wire has a resistance of $2.1\; \Omega$ at $27.5^{\circ} C$ and a resistance of $2.7\; \Omega$ at $100^{\circ} C$. Determine the temperature coefficient of resistivity of silver.

The cross-sections of wires made of the same material and having the same length are shown in the figure. What can be said about their resistances?

$A$ 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 .......... $^{\circ}C$.

In the following,$I$ refers to current and other symbols have their usual meaning. Choose the option that corresponds to the dimensions of electrical conductivity.

Why does the resistivity of a metal increase with an increase in temperature,or why does its conductivity decrease with an increase in temperature?