X-rays ionize electrode and discharge electroscope.

X-Rays ionize electrode and discharge electroscope. A metal spiral electrode is charged negatively (a Teflon rod is rubbed with cat fur) or positively (a Lucite rod is rubbed with Saran Wrap), and the presence of charge is demonstrated with the Braun electroscope. If a nearby X ray tube is turned on (see XX for explanation), the X rays discharge the spiral electrode. The X rays knock electrons off molecules of oxygen and nitrogen in the air. The oxygen and nitrogen molecules are left positively charged, and the electrons are picked up by other molecules which take on a negative charge. The presence of both positive and negative ions created by the X rays is sufficient to discharge the electrode. The apparatus is enclosed in a lead-lined box to protect viewers. Ref.:Modern College Physics by Harvey White, 6th ed., p. 768