$A$ cylindrical conductor of length $l$ and uniform area of cross-section $A$ has resistance $R$. Another conductor of length $2l$ and resistance $R$ of the same material has area of cross-section:

What happens to the resistance of a conductor when the length of the conductor is reduced to half?

Explain the term resistance. Give its $SI$ unit of measurement.

$A$ wire is $1.0 \, m$ long,$0.2 \, mm$ in diameter and has a resistance of $10 \, \Omega$. Calculate the resistivity of its material.

$(a)$ Explain why a conductor offers resistance to the flow of current.
$(b)$ Differentiate between conductor,resistor,and resistance.

$(a)$ Resistivity of iron is $10 \times 10^{-8} \; \Omega m$ and of mercury is $94 \times 10^{-8} \; \Omega m$. Which among iron and mercury is a better conductor? Give reason.
$(b)$ Resistivity of a material $A$ is in the range of $10^{10}-10^{14} \; \Omega m$ while that of $B$ is in the range of $10^{-6}-10^{-8} \; \Omega m$. Which of the two will behave as an insulator and why?