§3.1 稳恒电流分布的必要条件 Essential condition of steady current profile §3.2 稳恒电流体系的电场 Electric field of steady current system §3.3 矢势及其微分方程 Vector potential and differential equation §3.4 磁标势 Magnetic scalar potential §3.5 磁多极矩 Magnetic multipole moment §3.6 阿哈罗诺夫——玻姆效应 Aharonov-Bohm effects