\documentclass[crop,border=5,tikz,convert={outext=,
  command=\unexpanded{pdf2svg \infile\space\outfile\%02d.svg
    all}},multi=false]{standalone}
\usetikzlibrary{math,calc,through,shapes,patterns,decorations.pathmorphing}
\usepackage{tikz-3dplot}

\tdplotsetmaincoords{70}{120}

\begin{document}
\begin{tikzpicture}[>=latex,scale=1,tdplot_main_coords]
  \coordinate (A) at (-1,0,1);
  \coordinate (B) at (1,0,1);
  \def\myscale{1}
  \foreach \x in {-1,0,1}{
    \foreach \y in {-1,0,1}{
      \draw[thick,black!50!blue](\myscale*\x,-1.5,\myscale*\y+1)--(\myscale*\x,1.5,\myscale*\y+1);
      \draw[black!50!blue,->](\myscale*\x,1,\myscale*\y+1)--(\myscale*\x,0.05,\myscale*\y+1);
    }
  }
  \node[black!50!blue] at (0,-1.8,1.1) {$\vec{B}$};
  \draw[ultra thick,->,draw=black!50!green] (0,0,1)--(0,0,-0.9);
  \node[anchor=west,black!50!green] at (0,-0.7,-1){$\vec{F}_{\mathrm{m}}$};
  \draw[ultra thick,black] (-1,0,3.8)--(A)--(B)--(1,0,3.8);
  \draw[<->,black] ($(A)+(0,0,2.5)$)--($(B)+(0,0,2.5)$)
  node[midway,above]{$b$};
  \draw[ultra thick,->,black] (B)--+(0,0,2.5) node[left]{$I$};
  \draw[ultra thick,->,black] (A)--+(1,0,0);
  \draw[ultra thick,->,black] (-1,0,3.5)--+(0,0,-0.5);
\end{tikzpicture}
\end{document}