If the induction of a magnetic field at a point is $B$ and the energy density is $U$,then which of the following graphs is correct?

Select the dimensional formula of $\frac{B^2}{2\mu_0}$.

Two long straight parallel wires are a distance $2d$ apart. They carry steady equal currents flowing out of the plane of the paper. The variation of magnetic field $B$ along the line $xx'$ is given by:

$A$ very long wire $ABDMNDC$ is shown in the figure carrying current $I$. $AB$ and $BC$ parts are straight,long,and at a right angle. At $D$,the wire forms a circular turn $DMND$ of radius $R$. $AB$ and $BC$ parts are tangential to the circular turn at $N$ and $D$. The magnetic field at the centre of the circle is

$A$ charged particle enters a uniform magnetic field perpendicular to its initial direction,travelling in air. The path of the particle is seen to follow the path in the figure. Which of the statements $1-3$ is/are correct?
$[1]$ The magnetic field strength may have been increased while the particle was travelling in air.
$[2]$ The particle lost energy by ionising the air.
$[3]$ The particle lost charge by ionising the air.

The net magnetic field at the centre $O$ of the circle due to the current-carrying loop as shown in the figure is $(\theta < 180^\circ)$.