A square loop of side $a$ and carrying a current $I$ is suspended from an insulating hanger of a spring balance as shown in figure. The transverse magnetic field $B$ directed into the paper occurs only at the bottom side of the loop. When direction of current in the loop is reversed, the change in the reading of spring balance is

A current carrying loop is placed in a uniform magnetic field $B$ in different orientations I, II, III and IV as shown in the figure. The correct order of decreasing potential energy is

( $\hat{\mathbf{n}}=$ unit vector normal to the plane of the loop)

A current $i$ is flowing through a wire of length ' $L$ '. If it is made into a circular loop of one turn, then its magnetic moment is

It is found that a non-zero current element is unable to produce any magnetic field at a particular point. Then the angle between the current element and the position vector of that point with respect to the current element is