LaTeX Forum

 \draw [x,y,z]
    (0,0) -- (4,0) node[midway, above]
    (0,0) -- (0,-4)node[midway, left];

\begin{figure}
\fbox{
	\begin{minipage}[b]{0.5\textwidth}
		\centering	
			\begin{circuitikz}[european voltages]
				\draw (0,4)
				to [R=$R_1$, o-*] (0,2)
				to [C=$C_1$, *-o] (0,0);
			\end{circuitikz}
			\caption{Beispiel RC Glied}		
	\end{minipage}
}
	\begin{minipage}[b]{\linewidth}
		\centering
		\begin{tikzpicture}
		\draw [<->]
			  (0,-5) coordinate (B) node[below]{$Img$}
			-- (0,0) coordinate (A)
			-- (5,0) coordinate (C) node[right]{$Re$};
		\draw [->,thick, color=blue]
			(0,0) -- (4,0) node[midway, above]{$U\textsubscript{R1}$};
		\draw [->,thick, color=blue]
			(0,0) -- (0,-4)node[midway, left]{$U\textsubscript{C1}$};
		\draw [->,thick, color=blue]
			(0,0) -- (4,-4)node[midway, left]{$U$};
		\draw [->,thick, color=blue]
			(4,0) -- (4,-4)node[midway, left]{$U\textsubscript{C1}$};
		\draw
			[->, very thick, color=red] (0,0) -- (2,0)node[midway, above]{$i$};
		\draw
			pic ["$\varphi$", draw, ->, thick, angle radius =1cm, angle eccentricity=0.6] {angle=B--A--C};
		\end{tikzpicture}
		\caption{Zeigerdiagramm RC Glied}
	\end{minipage}

\end{figure}

EDIT: AHA, anscheinend liegt das Problem mit der fbox an dem Winkel phi, den ich im rechten Diagramm eintrage. Bzw. am Dollar oder an den Gänsefüßchen. Scheint da Probleme mit Babel zu geben.

\documentclass[parskip=full]{scrbook}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[autostyle=true,german=quotes]{csquotes}
\usepackage[ngerman]{babel}
\usepackage{lmodern}
\usepackage{booktabs}
\usepackage{marvosym}
\usepackage{tabularx}
\usepackage{multirow}
\usepackage{float}
\usepackage{tikz}
\usepackage{varwidth}
\usetikzlibrary{angles, intersections, snakes, quotes, babel}
\usepackage {tablefootnote}
\usepackage[european, europeanvoltages]{circuitikz}
\usepackage{caption}
\usepackage{graphicx}
\usepackage{gensymb}
\usepackage{todonotes}
\usepackage{amsmath, amsfonts, amssymb}
\usepackage[per-mode=fraction, decimalsymbol=comma]{siunitx}
\usepackage{babelbib}
\usepackage{textcomp}
\usepackage[hidelinks]{hyperref}
\begin{document}
	
\begin{figure}		
		\centering
		\fbox{			
			\begin{minipage}[b]{0.5\linewidth}
				\scalebox{0.7}
				{
					\begin{tikzpicture}
						\draw [<->]
						(0,-5) coordinate (B) node[below]{$Img$}
						-- (0,0) coordinate (A)
						-- (5,0) coordinate (C) node[right]{$Re$}
						pic [text="$\varphi$", draw, ->, thick, angle radius =1cm, angle eccentricity=0.6] {angle=B--A--C};
					\end{tikzpicture}
				}

			\end{minipage}
		}	
	\end{figure}
\end{document}

pic text=$\varphi$

\documentclass[parskip=full]{scrbook}
\usepackage[ngerman]{babel} 
\usepackage{tikz} 
\usetikzlibrary{angles, quotes, babel}

\usepackage{varwidth}

\begin{document} 
\begin{figure}
    \centering 
    \fbox{%
      \begin{varwidth}[b]{\linewidth} 
         \scalebox{0.7} 
         {%
            \begin{tikzpicture} 
               \draw [<->] 
               (0,-5) coordinate (B) node[below]{$Img$} 
               -- (0,0) coordinate (A) 
               -- (5,0) coordinate (C) node[right]{$Re$} 
               pic [pic text=$\varphi$, draw, ->, thick, angle radius =1cm, angle eccentricity=0.6] {angle=B--A--C};
            \end{tikzpicture}%
         }%
      \end{varwidth}%
    }
\end{figure}
\end{document}

\begin{document}
\begin{eqnarray}
	X_C = \frac{U_C}{I_C} = \frac{1}{\omega\cdot C} = \frac{1}{2\cdot \pi \cdot f \cdot C}\\
	\text{Umgestellt nach C}\\
	C = \frac{I_C}{2 \cdot \ \pi \cdot f \cdot U_C}
\end{eqnarray}
\end{document}

$U\textsubscript{R1}$

$U_{R_1}$