AB is a current-carrying conductor in the plane of the paper as shown in Figure 13.7. What are the directions of magnetic fields produced by it at points P and Q? Given r1 > r2, where will the strength of the magnetic field be larger?
AB is a current-carrying conductor in the plane of the paper as shown in Figure 13.7. What are the directions of magnetic fields produced by it at points P and Q? Given r1 > r2, where will the strength of the magnetic field be larger?

Solution: P puts you into the plane of paper, and Q takes you out of it. The strength of the magnetic field is greater at the point that is closer to the source, which is Q.