1. The problem statement, all variables and given/known data Two straight parallel wires are placed vertically on a wall. The distance between the wires is 12 cm and the current through each one is 7.5A. In the left wire the current is directed upwards and in the right one the current points downwards. Determine the magnetic field strength (or flux density), and its direction B in the following: a) A point between the wires. b) A point on the wall 12 cm to the left of the left wire. 2. Relevant equations a) B = k*I/d giving 12.5 μT from each wire. b) B = k*I/d giving 12.5 μT from the left wire and 6.25 μT from the right. 3. The attempt at a solution a) Now my first guess was to treat the magnetic field strength like waves; since the magnetic fields are in opposite directions they may at certain points strengthen each other and at some points even cancel out. So I thought that 25 μT (12.5+12.5) would be the maximum field strength and 0 μT would be the minimum.. However I'm also quite sure that the field between the wires is homogeneous giving a more specific value for B, perhaps the field strength is just 0 μT because they cancel out everywhere? b) This question works on the same principle as a), so do I subtract or add the field strengths? I'm guessing subtract because they are in opposite directions?