Find the equivalent resistance between points $A$ and $B$.

$A$ wire of length $25 \ m$ and cross-sectional area $5 \ mm^2$ having resistivity of $2 \times 10^{-6} \ \Omega \ m$ is bent into a complete circle. The resistance between diametrically opposite points will be (in $\Omega$)

$A$ wire of resistance per unit length $\rho_L = 10^{-6} \, \Omega/m$ is bent into a circle of diameter $2 \, m$. $A$ piece of wire of the same material is connected across the diameter $AB$. Find the resistance between $A$ and $B$.

$A$ wire of resistance $12 \, \Omega/m$ is bent to form a complete circle of radius $10 \, cm$. The resistance between its two diametrically opposite points, $A$ and $B$, as shown in the figure, is:

$A$ uniform metallic wire has a resistance of $18\,\Omega$ and is bent into an equilateral triangle. Then,the resistance between any two vertices of the triangle is .................. $\Omega$.

Two $10\,\Omega$ resistors are first connected in series and then in parallel. What is the ratio of the equivalent resistance in both cases?