答案1
答案2
\begin{equation*}
B_v = \dfrac{\mu_0 I_p}{4 \pi R} \left[ \ln \left( \dfrac{8 R}{a} \right) -dfrac{3}{2} + \beta_p + \dfrac{l_i}{2}\right]
\end{equation*}
\begin{equation*}
B_v = \dfrac{\mu_0 I_p}{4 \pi R} \left[ \ln \left( \dfrac{8 R}{a} \right) -dfrac{3}{2} + \beta_p + \dfrac{l_i}{2}\right]
\end{equation*}