11-2毕奥萨伐尔定律第十一章稳恒磁场 ldl dB R r=R+x X P rb loI r cos adl 2 Rc2兀R dB- lo ld/ B dl 4兀 R db- lo l cos adl B 4兀 2(x2+R11 – 2 毕奥—萨伐尔定律 第十一章 稳恒磁场 x x R * p 2 0 cos d 4π d r I l Bx = = l r I l B 2 0 cos d 4π 2 2 2 cos r R x r R = + = = R l r IR B 2π 0 3 0 d 4π 2 3 2 2 2 0 (2 x R ) IR B + = 2 0 d 4π d r I l B = o B d r I l d