Voltage Divider

\usepackage{circuitikz}

\begin{circuitikz}
  \draw (0,0) to[V=$V_{in}$] (0,3)
  to[R=$R_1$] (3,3)
  to[R=$R_2$] (3,0) -- (0,0);
  \draw (3,3) to[short, -o] (4,3) node[right]{$V_{out}$};
  \draw (3,0) to[short, -o] (4,0) node[right]{GND};
\end{circuitikz}