What is the resistance of an ideal voltmeter?

$V-I$ graphs for two wires $A$ and $B$ are shown in the figure. If both the wires are made of the same material and are of equal thickness,which of the two is of more length? Give justification for your answer.

What are the conditions under which $Ohm's$ law is not obeyed?

$(a)$ $(i)$ What is meant by saying that the potential difference between two points is $1 \, V$? $(ii)$ How much energy is given to $5 \, C$ of charge passing through a $12 \, V$ battery? $(b)$ Describe an activity with a necessary electric circuit to study the factors on which the resistance of a conducting wire depends.

What is the direction of conventional current?

Write the $SI$ unit of resistivity.