The equivalent resistance of the given circuit between the terminals $A$ and $B$ is $....\Omega$

An electrical cable consists of a single copper wire of radius $9 \ mm$. Its resistance is $5 \ \Omega$. If this cable is replaced by $6$ copper wires,each of radius $3 \ mm$,then the total resistance of the cable will be ............. $\Omega$.

$A$ wire is connected to a battery between the points $M$ and $N$ as shown in figure $(1)$. The same wire is bent in the form of a square and then connected to the battery between the points $M$ and $N$ as shown in figure $(2)$. Which of the following quantities increases?

The equivalent resistance of resistors connected in series is always

$A$ wire of resistance $R$ is bent into an equilateral triangle and an identical wire is bent into a square. The ratio of the equivalent resistance between the two end points of an edge of the triangle to that of the square is

$A$ wire of resistance $12 \,\Omega$ is bent into a circle. What is the equivalent resistance between two diametrically opposite points in $\Omega$?