Pre-Quantum Electrodynamics
Cross productc.m.va.cp
\begin{equation*}
{\bf A} \times {\bf B} = \left| \begin{array}{ccc} \hat{x} & \hat{y} & \hat{z} \\
A_x & A_y & A_z \\ B_x & B_y & B_z \end{array} \right|
= \left( A_y B_z - A_z B_y \right) \hat{x} + \left( B_z A_x - B_x A_z \right) \hat{y}
+ \left( A_x B_y - A_y B_x \right) \hat{z}
\end{equation*}
The cross product is distributive:
\[ {\bf A} \times ({\bf B} + {\bf C}) = {\bf A} \times {\bf B} + {\bf A} \times {\bf C} \]
The cross-product is anti-commutative:
\[ {\bf A} \times {\bf B} = - {\bf B} \times {\bf A} \]
this relation making plain that
\[ {\bf A} \times {\bf A} = 0. \]

Created: 2024-02-27 Tue 10:31