The Science Book

A CENTURY OF PROGRESS 179 according to its properties. He was wrong—the relative atomic weight of tellurium is in fact 127.6; it ...

LIGHT AND MAGNETISM ARE AFFECTATIONS OF THE SAME SUBSTANCE JAMES CLERK MAXWELL (1831 –1879) ...

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182 JAMES CLERK MAXWELL T he series of differential equations describing the behavior of electromagnetic fields developed by Sco ...

A CENTURY OF PROGRESS 183 in a single direction, easily created by bouncing a beam of light off a smooth reflecting surface) thr ...

184 JAMES CLERK MAXWELL Maxwell’s models Maxwell began to develop his theory of electromagnetism in a pair of papers published i ...

A CENTURY OF PROGRESS 185 frequencies and long wavelengths, but with the same overall speed of propagation—the form of electroma ...

186 RAYS WERE COMING FROM THE TUBE WILHELM RÖNTGEN (1845–1923) L ike many scientific discoveries, X-rays were first observed by ...

187 The first X-ray image was taken by Röntgen of his wife Anna’s hand. The dark circle is her wedding ring. On seeing the image ...

188 SEEING INTO THE EARTH RICHARD DIXON OLDHAM (1858–1936) T he shaking caused by earthquakes spreads out in the form of seismic ...

S- w av e sh ad ow (^) zon e 189 This model of an earthquake shows seismic waves passing through Earth and the “shadow zones” of ...

RADIATION IS AN ATOMIC PROPERTY OF THE ELEMENTS MARIE CURIE (1867–1934) ...

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192 MARIE CURIE L ike many major scientific discoveries, radiation was found by accident. In 1896, French physicist Henri Becque ...

A CENTURY OF PROGRESS 193 other than uranium). This led her to the belief that the radioactivity came from the uranium atoms the ...

194 MARIE CURIE isotopes are named after the total number of protons and neutrons, so the most common isotope of uranium, with 1 ...

A CENTURY OF PROGRESS 195 isotope has a half-life of 5,730 years. Carbon-14 is constantly being produced in the upper atmosphere ...

196 A CONTAGIOUS LIVING FLUID MARTINUS BEIJERINCK (1851–1931) T hese days, the word “virus” is all too familiar as a medical ter ...

197 This electron micrograph image shows particles of the tobacco mosaic virus at 160,000x magnification. The particles have bee ...

1900 –1945 A PARA SHIFT ...