The force between two long parallel wires is $F$ when each one of them carries a certain current $I$. If the current in each is halved,the force between them would be . . . . . . .

$A$ wire carrying current $I$ is tied between points $P$ and $Q$ and is in the shape of a circular arc of radius $R$ due to a uniform magnetic field $B$ (perpendicular to the plane of the paper,shown by $\times \times \times $) in the vicinity of the wire. If the wire subtends an angle $2\theta_0$ at the centre of the circle (of which it forms an arc),then the tension in the wire is:

Three infinite straight wires $A, B$ and $C$ carry currents as shown in the figure. The resultant force on wire $B$ is directed:

$A$ metal ring of radius $r = 0.5 \, m$ with its plane normal to a uniform magnetic field $B$ of induction $0.2 \, T$ carries a current $I = 100 \, A$. The tension in newtons developed in the ring is:

The magnetic field existing in a region is given by $\vec B = B_0 [1 + \frac{x}{l}] \hat k$. $A$ square loop of edge $l$ carrying current $I_0$ is placed with its edges parallel to the $x-y$ axes. Find the magnitude of the net magnetic force experienced by the loop.

The force acting per unit length on a very long straight conductor carrying a steady current of $1 \,A$ flowing from south to north is: (The horizontal component of the earth's magnetic field at the place is $3 \times 10^{-5} \,T$ and its direction is from geographical south to geographical north.)