+0 R dy r dQ dt r dt 2 5Fd=1+=(2n)= r dt 计算得H B= or dO 2兀R2dt 2兀R2dt 代入数据计算得4=1.1AB=1.11×10°Tc d d H dl I I I l = + = t Q R r H r d d (2π ) 2 2 = t Q R r t Ψ I d d d d 2 2 d = = t Q R r B d d 2π 2 0 = t Q R r H d d 2π 2 计算得 = 1.11 10 T −5 1.1A B = 代入数据计算得 I d = R c I P + Q − Q c * r I