# Optical Angular Momentum in Classical Electrodynamics

## TL;DR

This paper explores the nature of electromagnetic angular momentum in classical electrodynamics, demonstrating its relationship with energy, mechanical effects, and particle interactions through simple examples.

## Contribution

It provides a detailed analysis of electromagnetic angular momentum using Maxwell's equations and illustrates its physical implications and interactions.

## Key findings

- EM energy and angular momentum are closely related.
- Radiating EM angular momentum results in mechanical momentum transfer.
- Spin and orbital angular momenta induce different responses in particles.

## Abstract

Invoking Maxwell's classical equations in conjunction with expressions for the electromagnetic (EM) energy, momentum, force, and torque, we use a few simple examples to demonstrate the nature of the EM angular momentum. The energy and the angular momentum of an EM field will be shown to have an intimate relationship; a source radiating EM angular momentum will, of necessity, pick up an equal but opposite amount of mechanical angular momentum; and the spin and orbital angular momenta of the EM field, when absorbed by a small particle, will be seen to elicit different responses from the particle.

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Source: https://tomesphere.com/paper/1706.02407