Distance R = Distance((0,0), (r*Cos(45),r*Sin(45)), "$r$");
R.draw();
draw((-2r,0)--(-r,0){N}..(0,r){E}..{S}(r,0)--(2r,0));
-TwoTerminal Il = current((-1.5r,0), "I");
-TwoTerminal Ir = current((1.5r,0), "I");
+MultiTerminal Il = current((-1.5r,0), "I");
+MultiTerminal Ir = current((1.5r,0), "I");
dot("$P$", (0,0), S);
\end{asy}
\end{center}