$A$ piece of wire of resistance $4\,\Omega$ is bent through $180^o$ at its mid-point and the two halves are twisted together. The new resistance is ............ $\Omega$.

Four resistors,$100 \Omega, 200 \Omega, 300 \Omega$ and $400 \Omega$ are connected to form four sides of a square. The resistors can be connected in any order. What is the maximum possible equivalent resistance across the diagonal of the square (in $Omega$)?

The equivalent resistance of two resistors connected in series is $6 \ \Omega$ and their parallel equivalent resistance is $\frac{4}{3} \ \Omega$. What are the values of the resistances?

Three resistors are connected to form the sides of a triangle $ABC$. The resistances of the sides $AB$,$BC$,and $CA$ are $40\,\Omega$,$60\,\Omega$,and $100\,\Omega$ respectively. The effective resistance between the points $A$ and $B$ in $\Omega$ will be:

$A$ straight uniform wire of resistance $36 \Omega$ is bent in the form of a semi-circular loop. The effective resistance between the ends of the diameter of the semi-circular loop is

The power dissipated in the circuit shown in the figure is $30 \, W$. The value of $R$ is ............. $\Omega$.