What is the resistance of an ideal ammeter?

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 $1.4 \ V$?

Define resistivity of a material.

$A$ potential difference $V$ is applied across a conductor of length $L$ and diameter $D$. How is the resistance $R$ of the conductor affected,when in turn $(i)$ $V$ is halved,$(ii)$ $L$ is halved,and $(iii)$ $D$ is doubled? Justify your answer in each case.

On which factors does the resistivity of a conducting wire depend?

What is the unit of resistance?