The resistivity of a material is found to be $10^8 \Omega-\mathrm{m}$, then the material would be

A metal wire of length $L$ and radius $r$ has a resistance $R$. If a wire of the same metal of length $2 L$ and radius $3 r$ is taken, then what will be its resistance?

Balancing point of a potentiometer shifts from a length of 60 cm to 40 cm by shunting the cell with a $4 \Omega$ resistance. What is the internal resistance of the cell?

Find the equivalent resistance between point $A$ and $B$ in the following circuit. (The resistance of each resistor is $R$ )