Two parallel wires are carrying electric currents of equal magnitude and in the same direction. They exert

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 $2$ times and its direction is reversed. The distance between them is also increased to $3d$. The new value of force between them is:

When current passing through two parallel wires flows in the same direction,the force between them is $......$,while when current passes in opposite directions through the same wires,the force between them is $......$ (attraction,repulsion).

$A$ fixed horizontal wire carries a current of $200\, A$. Another wire having a mass per unit length of $10^{-2}\, kg/m$ is placed below the first wire at a distance of $2\, cm$ and parallel to it. How much current must be passed through the second wire if it floats in air without any support? What should be the direction of current in it?

Currents of $10\, A$ and $2\, A$ are passed through two parallel thin wires $A$ and $B$ respectively in opposite directions. Wire $A$ is infinitely long and the length of wire $B$ is $2\, m$. The force acting on the conductor $B$,which is situated at a distance of $10\, cm$ from $A$,will be:

$A$ current-carrying rectangular loop $PQRS$ is made of uniform wire. The lengths are $PR = QS = 5\,cm$ and $PQ = RS = 100\,cm$. If the ammeter current reading changes from $I$ to $2I$,the ratio of magnetic forces per unit length on the wire $PQ$ due to wire $RS$ in the two cases respectively,$f_{PQ}^{I} : f_{PQ}^{2I}$,is: