What length of the wire of specific resistance $48 \times 10^{-8} \, \Omega \, m$ is needed to make a resistance of $4.2 \, \Omega$ (in $.1$)? (Diameter of wire = $0.4 \, mm$)

The cross-sections of wires made of the same material and having the same length are shown in the figure. What can be said about their resistances?

What is the resistance between the rectangular faces of a block with resistivity $3 \times 10^{-7} \, \Omega \cdot m$ and dimensions $1 \, cm \times 1 \, cm \times 100 \, cm$?

If the ratio of the masses of wires of the same material is $1 : 3 : 5$ and the ratio of their lengths is $5 : 3 : 1$,what is the ratio of their resistances?

$A$ cylindrical wire $P$ has resistance $10 \ \Omega$. $A$ second wire $Q$ has length and diameter half that of $P$. If the material of both the wires is same,then the resistance of wire $Q$ is (in $\Omega$)

In the given circuit,the lengths of $AB$ and $BC$ are equal. The radius of $AB$ is three times that of $BC$. What is the ratio of the potential difference across $AB$ to that across $BC$?