What are the factors on which the resistivity of a material depends?

State the formula correlating the electric current flowing in a conductor and the voltage applied across it. Also, show this relationship by drawing a graph. What would be the resistance of a conductor, if the current flowing through it is $0.35 \ A$ when the potential difference across it is $1.4 \ V$?

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

If the cross-sectional area of a conducting wire is doubled,what will be the effect on its resistance?

$A$ cylinder of a material is $10\, cm$ long and has a cross-section of $2\, cm^{2}$. If its resistance along the length is $20\, \Omega$,what will be its resistivity in number and units?

What will happen to the current flowing through a conductor,if the potential difference is doubled?