Two long parallel conducting wires carry current I in same direction, placed at distance b. Force per unit length of wire is

Two long parallel conducting wires carrying currents are seperated by a distance 'x' . Work done per unit length in changing the distance between the wires is proportional to

Two long parallel wires carry equal current I flowing in the same direction are at a distance 2d apart. The magnetic field B at a point lying on the perpendicular line joining the wires and at a distance x from the midpoint is

Two long parallel wires carry equal current I flowing in the same direction are at a distance 2d apart. The magnetic field B at a point lying on the perpendicular line joining the wires and at a distance x from the midpoint is