André-Marie Ampère

Physicist and mathematician — André-Marie Ampère (Lyon 1775 – Marseille 1836) was a French physicist and mathematician, largely self-taught. He is considered the founder of electrodynamics, the science that studies the interactions between electric currents, a discipline he himself named. After learning in 1820 of Ørsted’s experiment, in which a current deflects a magnetic needle, within a few weeks he developed the mathematical theory linking electricity and magnetism, showing that two current-carrying wires attract or repel each other. His work laid the foundations for the nineteenth-century unification of electric and magnetic phenomena. In his honour, the unit of measurement of current intensity is called the ampere.

Trivia

His life was marked by tragedy: his father was guillotined during the Terror of the French Revolution, and shortly afterwards his beloved wife also died.

Theories and contributions

• Ampère’s law — The circulation of the magnetic field along a closed line is proportional to the enclosed current: $\oint \vec{B}\cdot d\vec{l}=\mu_0 I$.
• Force between current-carrying wires — Two parallel conductors attract or repel each other with a force per unit length $\frac{F}{L}=\frac{\mu_0 I_1 I_2}{2\pi d}$.

Present in chapters

17 19 Z

Linked atoms

11 linked atoms.

17 Il campo magnetico

• Ampère’s theorem
• Magnetic field of a conducting plane
• The solenoid

19 Le equazioni di Maxwell e le onde elettromagnetiche

• The four equations (first, incomplete version)
• The capacitor paradox
• The displacement current
• The magnetic field inside the charging capacitor
• Maxwell’s four equations
• Speed of electromagnetic waves
• Maxwell and unification: when c emerges from the equations

Z Appendice — Maturità

• Ministerial syllabus and map of the book