What is the resistance of an ideal voltmeter?

$A$ conducting wire offers resistance to the flow of electrons because electrons repel each other in the wire.

$A$ 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?

State the factors on which the resistance of a cylindrical conductor depends. How will the resistance of a conductor change if it is stretched so that its length is doubled?

Two students perform experiments on series and parallel combinations of two given resistors $R_{1}$ and $R_{2}$ and plot the following $V-I$ and $I-V$ graphs. Which of the graphs is (are) correctly labelled in terms of the words 'series' and 'parallel'? Justify your answer.

The potential difference between the terminals of an electric heater is $60\, V$ when it draws a current of $4\, A$ from the source. What current will the heater draw,if the potential difference is increased to $120\, V$ (in $, A$)?