The force exerted by a magnetic field on a wire having length $L$ and current $I$ is perpendicular to the wire and given as $|F| = IL|B|$. An experimental plot shows $|F|$ as a function of $L$. The plot is a straight line with a slope $S = (10 \pm 1) \times 10^{-5} \ T$. The current in the wire is $I = (15 \pm 1) \ mA$. The percentage error in $B$ is:

$A$ straight horizontal long wire carries $30 \ A$ current. The linear mass density of the wire is $45 \ g/m$. What is the magnitude of the magnetic field needed to balance the wire in air?

$A$ square loop $ABCD$ of side length $L$ carrying a current $i$ is placed near and coplanar with a long straight conductor $XY$ carrying a current $I$. The distance between the wire $XY$ and the nearest side of the loop is $L/2$. The net force on the loop will be:

Two infinitely long parallel conducting wires $A$ and $B$ carry currents $I$ and $2I$, respectively, in the same direction. The wire $A$ has uniform mass per unit length $\lambda$ and lies on an insulated floor. The wire $B$ is kept fixed at a height $h$ above the floor. The minimum magnitude of $h$ so that the wire $A$ does not rise from the floor is : [$g$ is the acceleration due to gravity and $\mu_0$ is the permeability of free space]

$A$ straight current-carrying conductor is placed such that the current flows out of the plane of the paper. The conductor is placed between the poles of two magnets,as shown in the figure. The conductor will experience a force in the direction towards:

What is the force per unit length between the two wires shown in the figure? [${\mu _0} = 4\pi \times {10^{ - 7}} \text{ T}\,m/A$]