$A$ straight wire of resistance $18 \Omega$ is bent in the form of an equilateral triangular loop. The effective resistance between any two vertices of the triangle is (in $\Omega$)

The current $I$ flowing through the given circuit will be $.....A$.

$A$ 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 $B$.

Resistors of $10\, \Omega, 5\, \Omega, 7\, \Omega$, and $3\, \Omega$ are connected along the sides $AB, BC, CD$, and $DA$ of a square, respectively. A resistor of $10\, \Omega$ is connected across the diagonal $AC$. What is the equivalent resistance between points $A$ and $B$ in $\Omega$?

$A$ wire of resistance $R$ is bent to form a circular ring. Find the equivalent resistance between two points $X$ and $Y$ on its circumference. (The angle $XOY = \alpha$ is given.)

Two conductors of same length are connected in parallel as shown in the figure. Their cross-sectional areas are $A_1$ and $A_2$ and their resistivities are $\rho_1$ and $\rho_2$ respectively. The equivalent resistivity of this combination is