Discovery of X-Rays

DOE-HDBK-1109-97

Radiological Safety Training for Radiation-Producing (X-Ray) Devices

Instructor's Guide

Lesson Plan

Instructor's Notes

EARLY HISTORY OF X-RAYS

Discovery of X-Rays.

X-rays were discovered in 1895 by German

scientist Wilhelm Roentgen. On November 8,

1895, Roentgen was investigating high-voltage

electricity and noticed that a nearby phosphor

glowed in the dark whenever he switched on the

apparatus. He quickly demonstrated that these

unknown "x" rays, as he called them, traveled in

straight lines, penetrated some materials, and were

stopped by denser materials. He continued

experiments with these "x" rays and eventually

produced an X-ray picture of his wife's hand

showing the bones and her wedding ring. On

January 1, 1896, Roentgen mailed copies of this

picture along with his report to fellow scientists.

By early February 1896, the first diagnostic X-ray

in the United States was taken, followed quickly by

the first X-ray picture of a fetus in utero. By March

of that year, the first dental X-rays were taken. In

that same month, French scientist Henri Becquerel

was looking for fluorescence effects from the sun,

using uranium on a photographic plate. The

weather turned cloudy so he put the uranium and

the photographic plate into a drawer. When

Becquerel developed the plates a few weeks later,

he realized he had made a new discovery. His

student, Marie Curie, named it radioactivity.