Three long straight wires are connected in parallel to each other across a battery of negligible internal resistance. The ratio of their resistances is $3 : 4 : 5$. What is the ratio of the distances of the middle wire from the others if the net force experienced by it is zero?

In the figure,the cube has an edge length of $40\,cm$. Four straight segments of wire $ab$,$bc$,$cd$,and $da$ form a closed loop that carries a current $I = 5\,A$. $A$ uniform magnetic field of $0.02\,T$ is in the $+y$-direction. The ratio of the magnetic force on segment $ab$ to the magnetic force on segment $bc$ is:

An isosceles triangular current-carrying loop is placed in a uniform magnetic field $\overrightarrow{B_{o}}$ directed perpendicular to the plane of the loop,as shown in the figure. The net magnetic force on the loop is:

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

$A$ 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?

$A$ square loop $ABCD$ of side $L$ carrying a current $I_1$ is placed at a distance $(L/3)$ from a straight conductor $XY$ carrying current $I_2$. The loop and the conductor are coplanar. The net force on the loop will be ($\mu_0$ = magnetic permeability).