A rectangular loop of sides $10 \mathrm{cm}$ and $5 \mathrm{cm}$ carrying a current $I$ of $12 \mathrm{A}$ is placed in different orientations as shown in the figures below:

         

       

If there is a uniform magnetic field of $0.3 \mathrm{T}$ in the positive z direction, in which orientations the loop would be in $\left(\mathrm{i}\right)$ stable equilibrium and $\left(\mathrm{ii}\right)$ unstable equilibrium?

A circular loop of radius $r$ and mass $m$ is placed in $x-y$ plane as shown in the figure below. A uniform magnetic field $B$ is applied parallel to $x$-axis. What should be the value of current $I$ flowing in the loop such that one edge of the loop just gets lifted from the table?

Four wires each of length $4.0 \mathrm{m}$ are bent into four loops $\mathrm{I}$, $\mathrm{II}$, $\mathrm{III}$ and $\mathrm{IV}$ and then suspended into uniform magnetic field. Same current is passed in each loop. Then the couple will be the highest on loop