The Nature of X-Rays and the Structure of Atoms

Summary

Charles Glover Barkla’s *The Nature of X-Rays and the Structure of Atoms* argues that X-rays are not material particles but a previously unknown variety of light—ether waves of very short wavelength, distinguished by their remarkable power to penetrate opaque substances. The book traces the discovery of X-rays by Roentgen in 1895, who found they could pass through stone, flesh, and black paper to expose a chemical screen, and links this to the broader revolution in physics that followed the discovery of radium in 1898. Barkla explains that these advances proved atoms are real but not indivisible; they are composed of smaller particles, including electrons, which X-rays can eject from atoms. A reader takes away a concrete understanding of X-rays as short-wavelength light, the experimental basis for the electronic constitution of matter, and how these discoveries dismantled the older notion of the atom as an indivisible unit.

Key concepts

• Ether waves — The medium through which X-rays, like all light, propagate as vibrations, though modern theories later dispensed with this conception.
• Crookes tube — The evacuated glass apparatus used by Roentgen, which produced X-rays when covered and caused a nearby chemical screen to glow.
• Electrons — Definite entities produced by the passage of X-rays through air, which can traverse matter in straight paths or be deflected by magnetic fields.
• Radio-active elements — Substances like radium, discovered in 1898, that revealed a new property of matter and led to the understanding that atoms can be broken up.
• Phosphorescence — The property of certain substances to become luminous after exposure to sunlight, which Becquerel investigated in 1896 to test if they produce X-rays.
• Spectroscope — An instrument that detects variations in light wavelengths, used to show that X-rays differ from visible light only in having shorter wavelengths.

From the book

Title: The Nature of X-Rays and the Structure of Atoms by Charles Glover Barkla

Popular questions readers ask

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