# [SCI] Classical Electromagnetism

**Classical Electromagnetism** is the unified theory of electric and magnetic phenomena, culminating in Maxwell's equations (1865), which revealed that light is an electromagnetic wave.

## Overview

Michael Faraday discovered electromagnetic induction (1831) and introduced the concept of field lines, providing a physical picture of how electricity and magnetism are related. James Clerk Maxwell unified all known electric and magnetic phenomena into four differential equations, predicting that oscillating fields propagate as waves at the speed of light. Heinrich Hertz confirmed electromagnetic waves experimentally (1887), opening the path to radio and all wireless technology.

Maxwell's equations remain exact in the classical domain; they are Lorentz-invariant and were the empirical motivation for special relativity.

## Key Figures & Recognition

- **Michael Faraday** (1791–1867): Electromagnetic induction, field concept. No Nobel (predates prize).
- **James Clerk Maxwell** (1831–1879): *A Treatise on Electricity and Magnetism*, 1873. No Nobel (died young).
- **Heinrich Hertz** (1857–1894): Confirmed EM waves (1887). No Nobel (died young).

## Seminal Papers

- Maxwell, J.C. "A Dynamical Theory of the Electromagnetic Field." *Phil. Trans. R. Soc.* 155 (1865).
- Hertz, H. "Über Strahlen elektrischer Kraft." *Ann. Phys.* 272 (1888).

## What This Enables

- **[SCI] Electromagnetic Wave Theory** — Maxwell's equations directly predict transverse wave solutions propagating at the speed of light.
- **[TECH] Telegraph & Telephone** — Faraday's induction laws make it possible to transmit encoded electrical current pulses along a wire.
- **[TECH] Electric Power Grid** — Electromagnetic induction (Faraday, 1831) is the operating principle of every generator and transformer.
- **[SCI] Electrochemistry** — Faraday's laws of electrolysis — charge drives chemical reactions — emerge directly from the EM framework.
- **[TECH] Electric Motors & Power Electronics** — Faraday's 1821 electromagnetic rotation experiment is the direct prototype of every electric motor.

## Discovery Character
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**Surprise level**: Extreme — Before Maxwell, electricity, magnetism, and light were three entirely separate domains. Their unification into one set of four equations — and the prediction that light itself is an electromagnetic wave — was wholly unanticipated.
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**Mode**: Hybrid. Faraday was a relentless systematic experimenter guided by physical intuition (field lines, lines of force). Maxwell provided the mathematical closure, predicting electromagnetic waves from pure theory with no experimental anomaly demanding them. Hertz's 1887 confirmation was then a deliberate experimental search for something theory said must exist — the rare case of experiment following prediction by 22 years.
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# Parents

* [SCI] Newtonian Mechanics
* [SCI] Newtonian Mechanics
* [TECH] Precision Instruments