$A$ student has $10$ resistors of resistance $r$. The minimum resistance made by him from given resistors is

$A$ wire has a resistance of $12 \, \Omega$. It is bent in the form of an equilateral triangle. The effective resistance between any two corners of the triangle is

$A$ wire of resistance $20 \Omega$ is divided into $10$ equal parts. $A$ combination of two parts are connected in parallel and so on. Now,the resulting pairs of parallel combinations are connected in series. The equivalent resistance of the final combination is . . . . . . $\Omega$.

Four resistances of $100 \ \Omega$ each are connected in the form of a square. Then,the effective resistance along the diagonal points is ............. $\Omega$.

Find the equivalent resistance between the points $a$ and $b$ in $\Omega$.

$A$ wire has a resistance of $24 \ \Omega$ and is bent into the shape shown below. The effective resistance between $A$ and $B$ is ............. $\Omega$.