The amplitude of an electromagnetic (EM) wave does not affect its physical size in space. The electric field (E) and magnetic field (B) of an EM wave oscillate orthogonally to each other and to the direction of propagation, but their amplitude only influences the intensity or brightness of the wave, not the volume it occupies. For example, the equations \textbf{E}_1=\textbf{E}_0\cos(\textbf{k}\cdot\textbf{r}-\omega t) and \textbf{E}_2=2\textbf{E}_0\cos(\textbf{k}\cdot\textbf{r}-\omega t) illustrate that the only difference between two EM waves is their amplitude. Furthermore, the amplitude is independent of the beam's diameter, which can vary while maintaining either high or low amplitude.
PREREQUISITESPhysicists, electrical engineers, and students studying electromagnetism or wave theory will benefit from this discussion, particularly those interested in the properties and behaviors of electromagnetic waves.