Two long conductors, separated by a distance $d$ carry currents $I_1$ and $I_2$ in the same direction. They exert a force $F$ on each other. Now the current in one of them is increased to two times and its direction is reversed. The distance is also increased to 3$d$. The new value of the force between them is

Loop $ABCD$ and long straight wire are in the same plane. Side $CD=2AB$. Distance between long straight wire and $AB$ is equal to the distance between $AB$ and $CD$. Net force on the loop is 

A rectangular loop carrying a current $i$ is situated near a long straight wire, such that the wire is parallel to one of the sides of the loop, and is in the plane of the loop. If a steady current $I$ is established in the wire as shown in the figure, the loop will