LaTeX 8.1 Inserting Figures

• Include graphic package: \usepackage{graphicx}
• Declare float container: \begin{figure}[htbp] ... \end{figure}
• Center image horizontally: \centering
• Specify image scale and path: \includegraphics[width=0.55\textwidth]{fig1.png}
• Add caption and reference label: \caption{...} and \label{fig:...}

The graphicx package provides the standard \includegraphics command for inserting bitmap (PNG, JPEG) and vector (PDF, EPS) figures into LaTeX documents. The optional positioning parameter [htbp] instructs the LaTeX float positioning engine to prioritize placement: here, at the top of the page, at the bottom of the page, or on a separate float page.

• Include optics ray diagram using \includegraphics[width=0.65\textwidth]{optics_rings.png}
• Relate physical geometry $t \approx r^2 / (2R)$ to path difference $\Delta$
• Derive dark fringe condition: $2t + \lambda/2 = (2n+1)\lambda/2 \implies r_n^2 = n R \lambda$

In physics publications, diagrams are sized relative to the page geometry using fractional dimensions like width=0.65\textwidth. This ensures consistent scaling across different document classes and margins.