Moving Charges And Magnetism

Two infinitely long parallel conducting wires $A$ and $B$ carry currents $I$ and $2 I$, 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.]