% miko:type: atomic
% miko:title: Poynting Vector
% miko:summary: The energy flux carried by an electromagnetic field.
% miko:tags: em
% miko:difficulty: undergrad
% miko:related: maxwell-equations, wave-equation
% miko:keywords: energy flux, electromagnetic field, conservation

\documentclass{article}
\usepackage{amsmath}
\title{Poynting Vector}
\begin{document}
\maketitle

\section{Definition}

The Poynting vector is

$$
\mathbf S=\frac{1}{\mu_0}\mathbf E\times\mathbf B.
$$

It points in the direction of electromagnetic energy flow.

\section{Plane Wave}

For a plane electromagnetic wave, $\mathbf E$, $\mathbf B$, and $\mathbf S$ are
mutually perpendicular.

\end{document}
