How do i get the two circuits to display side by side?

\documentclass[11pt, a4paper]{article}
\usepackage{fullpage}
\usepackage{circuitikz}
\usepackage{enumerate}
\usepackage{SIunits}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\begin{document}
\begin{figure}[h]
\centering
\begin{subfigure}[t]{0.3\textwidth}
\centering
\begin{circuitikz}[ scale=1.2, american voltages]\draw
(0,0) -- (3,0) to[short, -o](3,0)
(0,1.5) to [R, l=$10 \kilo \ohm$] (3,1.5) to[short, -o](3,1.5)
(3,1.5) to [open, v = $V_c$] (3,0)
(0,0) to [V, l=$V_i$] (0,1.5)
;\end{circuitikz}
\end{subfigure}

\begin{subfigure}[t]{0.3\textwidth}
\centering
\begin{circuitikz}[ scale=1.2, american voltages]\draw
(0,0) -- (3,0) to[short, -o](3,0)
(0,1.5) to [R, l=$10 \kilo \ohm$] (3,1.5) to[short, -o](3,1.5)
(3,1.5) to [open, v = $V_c$] (3,0)
(0,0) to [V, l=$V_i$] (0,1.5)
;\end{circuitikz}
\end{subfigure}
\end{figure}
\end{document}

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@SašoŽivanović please either post an answer, or vote to close :) –  cmhughes Feb 23 '13 at 17:19

The empty line between the two subfigure environments created a paragraph between them. If you want the figures to be displayed side by side, there should be no paragraph; you will probably want some space.

So, to put the figures side by side, you could simply delete the empty line between them. The figures would still be separated by a space, since for TeX, a newline (but not a double newline) is the same as a space.

Below, I have however put a % on the line dividing the subfigures. I did this for a psychological effect: it is easier for the author to find the break between the figures. (% is a comment character for TeX, thus it does nothing but preventing TeX from seeing an empty line and making a paragraph there.)

\documentclass[11pt, a4paper]{article}
\usepackage{fullpage}
\usepackage{circuitikz}
\usepackage{enumerate}
\usepackage{SIunits}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}

\begin{document}
\begin{figure}[h]
\centering
\begin{subfigure}[t]{0.3\textwidth}
\centering
\begin{circuitikz}[ scale=1.2, american voltages]\draw
(0,0) -- (3,0) to[short, -o](3,0)
(0,1.5) to [R, l=$10 \kilo \ohm$] (3,1.5) to[short, -o](3,1.5)
(3,1.5) to [open, v = $V_c$] (3,0)
(0,0) to [V, l=$V_i$] (0,1.5)
;\end{circuitikz}
\end{subfigure}
%
\begin{subfigure}[t]{0.3\textwidth}
\centering
\begin{circuitikz}[ scale=1.2, american voltages]\draw
(0,0) -- (3,0) to[short, -o](3,0)
(0,1.5) to [R, l=$10 \kilo \ohm$] (3,1.5) to[short, -o](3,1.5)
(3,1.5) to [open, v = $V_c$] (3,0)
(0,0) to [V, l=$V_i$] (0,1.5)
;\end{circuitikz}
\end{subfigure}
\end{figure}
\end{document}


If you want to control the (horizontal) spacing between the circuits, you can use various LaTeX's commands: e.g. \quad qill make a "quadraple" space. The general command is \hspace, e.g. \hspace{1.1cm} will put 1.1cm of space between the circuits.

Note that if you need to be really precise, you have to take care that no "extra" space gets in your line: the usual trick is to use a percent % sign to end the line (remember, for TeX, a single newline is the same as a space). Thus, the following would put precisely 1.1cm of horizontal space between the circuits:

 ...
\end{subfigure}%
\hspace{1.1cm}%
\begin{subfigure}[t]{0.3\textwidth}
...

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Thanks! Works like a charm! –  Charles Feb 23 '13 at 18:24