Is there a way to adjust the appearance of an voltage label between two points? For default the label $U_1$
will be placed midway of the voltage arrow, but I want it to appear at a point realtive to the length of the voltage arrow, for example at quarter way or at 70% way.
\usepackage[americaninductors, straightvoltages]{circuitikz}
\begin{document}
\begin{circuitikz}
\draw (0,0) to [open, v^=$U_1$] (2,0);
\end{circuitikz}
\end{document}