So here is the problem: 2 thin straight wires carrying steady currents are placed perpendicular as shown in the attached file. The magnetic field at all points of the red wire due to the blue one is downward through the screen, and thus, the net force F exerting on the red wire due to the blue wire is upward and parallel to the blue wire. Similarly, the force F' that the blue wire experiences due to the red one is parallel to the red wire. So F and F' don't equal, which violates the Newton's 3rd law! Was I wrong at some point here? Thank you.