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

$A$ 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?

Three identical resistances $A$,$B$,and $C$ are connected as shown in the given figure. The heat produced will be maximum in:

In this circuit,the value of $I_2$ is (in $A$)

$A$ Copper $(Cu)$ rod of length $25 \, cm$ and cross-sectional area $3 \, mm^2$ is joined with a similar Aluminium $(Al)$ rod as shown in the figure. Find the resistance of the combination between the ends $A$ and $B$ (in $m\Omega$).
(Take Resistivity of Copper $= 1.7 \times 10^{-8} \, \Omega \cdot m$,Resistivity of Aluminium $= 2.6 \times 10^{-8} \, \Omega \cdot m$)

In the given figure,switches $S_{1}$ and $S_{2}$ are initially open. What is the equivalent resistance across $a b$ when the switches $S_{1}$ and $S_{2}$ are closed? (in $\Omega$)