Textbook Guide Physics: European Route E40, Vacuum Permeability, Electromagnet

Two power lines lie parallel to each other, separated by 20 cm.They carry parallel currents, both of
magnitude 3000 A.
a) Find the force per unit length on one line due to the current inthe other line. Is the force attractive or
repulsive?
b) Consider a point P lying halfway between the two lines.
- What is the magnitude of the magnetic field at P due to the twocurrents?
- If the currents in the two lines were antiparallel, what would bethe magnitude of the magnetic field
at P?

Please help me!!!!Thank you so much

Two long parallel wires separated by a distance d each carry a constant electric current I. Find an expression for the magnitude of the force per unit length of wire (F/L) on each wire from the magnetic field of the other wire. Also find the direction of the force on each wire if the two currents are either parallel or anti parallel.

Two wires, each having a weight per unit length 10^-4 N/m, are parallel, with one directly above the other. Assume that the wires carry currents that are equal in magnitude and opposite in direction. The wires are 0.1 m apart and the sum of the magnetic force and gravitational force on the upper wire is zero. Find the magnitude of the current in the wires. (Neglect the Earth's magnetic field)