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.

If the diameter of a conducting wire is doubled,how many times does its resistance become?

$A$ piece of wire of resistance $6 \, \Omega$ is connected to a battery of $12 \, V$. Find the amount of current flowing through it. Now,the same wire is redrawn by stretching it to double its length. Find the resistance of the new (redrawn) wire.

What is the unit of resistance?

Calculate the resistance of an electric bulb which allows a $10 \ A$ current when connected to a $220 \ V$ power source. (in $\Omega$)