# Interference Between Source-Free Radiation and Radiation from Sources: Particle-Like Behavior for Classical Radiation

## TL;DR

This paper demonstrates how classical electromagnetic radiation can exhibit particle-like behavior through interference effects between source-free standing waves and radiation from a current pulse, illustrating concepts related to photon-like phenomena.

## Contribution

It introduces a simple electrodynamics problem showing classical interference effects that mimic particle-like behavior, connecting classical waves to photon concepts.

## Key findings

- Interference patterns depend on phase and magnitude relations.
- Symmetric radiation occurs when source-free waves are negligible.
- Asymmetric, particle-like radiation emerges when source-free waves are significant.

## Abstract

A simple junior-level electrodynamics problem is used to illustrate the interference between a source-free standing plane wave and a wave generated by a pulse in a current sheet. Depending upon the relative phases between the standing wave and the current pulse and also upon the relative magnitudes, we can find quite different patterns of emitted energy and momentum. If the source gives a large radiation pulse so that the source-free plane wave can be neglected, then the radiation spreads out symmetrically on either side of the current sheet. However, if the radiation sheet gives a pulse with fields comparable to those of the standing wave, then we can find a single radiation pulse moving to the right while the current sheet recoils to the left, or the situation with the directions reversed. The example is a crude illustration of particle-like behavior arising from conventional classical electromagnetic behavior in the presence of source-free radiation. The discussion makes contact with the ideas of photons in modern physics.