Week 6: Michael Faraday
Chapter 9, “Nineteenth-Century Physical Science”
Classical physical science: The electrodynamic interpretation of the universe complemented the existing mechanical universe.
Unsolved problems: The indivisible atom failed to account for atomic spectra and bonds.
Radioactivity: Becquerel's discovery of radioactivity in 1896 challenged the law of conservation of energy, which Einstein later accounted for with E = mc2.
Light Theory: In the early 1800s, the wave theory of light became dominant, reviving the idea of luminiferous ether.
Speed of Light: Physicists sought to calculate the speed of light, with Michelson's experiments questioning whether it had an absolute value.
Ether: Michelson's ether drift experiment did not detect the expected direction-dependent difference in the speed of light, casting doubt on the ether's presence. Einstein's theory of special relativity dispensed with the ether.
Molecular Structure: Chemical studies progressed to determine the arrangement of atoms in a molecule, with Kekulé and Couper providing structural formulas for carbon compounds.
Periodic Table: Mendeleev published his Periodic Table in 1869, providing a classification system for elements.
Atomic Weight: Chemists agreed on oxygen (O=16) as the standard for atomic weight determinations.
Tools for Analysis: The Bunsen burner and spectroscope aided chemists in analyzing compounds.
Thermodynamics: Thermodynamics became an integral part of theoretical and physical chemistry.
Determinism: Determinism dominated nineteenth-century science, but discoveries between 1895 and 1915 challenged it.
Transformation of Science: Discoveries such as x-rays, radioactivity, and the electron, along with the quantum theory and relativity, transformed classical physical science.
Technology and Environment: Technological advancements led to environmental problems like pollution, which were largely ignored until the second half of the twentieth century.
Relation between Electricity and Magnetism: Nineteenth-century scientists established the relationship between electricity, magnetism, and light.
Oersted's Discovery: Oersted's experiment in 1820 demonstrated the connection between electric and magnetic forces.
Ampere's Contributions: Ampere's experiments further explored electricity and magnetism, establishing the right-hand rule.
Ampere's Electrical Theory of Magnetism: Ampere proposed that electric molecules circling in a substance produce a magnetic effect.
Faraday's Achievements: Faraday demonstrated the motor principle, electromagnetic induction, and the generator and transformer principle.
Motor Principle: Faraday's experiment showed that a magnet rotates around a fixed conductor when an electric current is flowing, converting electrical energy to mechanical motion.
Electromagnetic Induction: Faraday discovered that moving a magnet in a coil of wire induced an alternating current, leading to the principle of the electrical generator and transformer.
Transformer: Faraday demonstrated the principle of the transformer, where the voltage in coils depends on the number of windings.
Lines of Force: Faraday used lines of force to explain how force acted at a distance.
Electromagnetic Field: Maxwell called the lines of force an electromagnetic field and developed the fundamental equations of electromagnetism.
Electrolysis: Faraday's laws of electrolysis related electric charge, current, time, and mass of substance deposited.
Ohm's Law: Ohm's law relates voltage, current, and resistance in a conductor.
Electrical Units: The International Congress of Electrical Engineers adopted volt, ampere, and ohm as units of potential, current, and resistance.