What is the resistance of an ideal voltmeter?

What is meant by $1$ ohm resistance?

Use the data in the table to answer the following: Which among iron and mercury is a better conductor?
< p style="text-align:center"> < span style="font-size:14px"> Electrical resistivity of some substances at $20\,^oC$

Material	Resistivity $(\Omega \,m)$
Iron	$10.0 \times 10^{-8}$
Mercury	$94.0 \times 10^{-8}$

The potential difference across the terminals of a cell is $1.5 \ V$. If it is connected with a resistance of $30 \ \Omega$,calculate the current flowing through the circuit. (in $A$)

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

$Ohm's$ law is a relation between the power used in a circuit to the current and the potential difference.