Dental Radiology Foundation Chain & Physics Practice Test 2026 - Free Dental Radiology Practice Questions and Study Guide

Cathode rays are streams of electrons produced at the cathode by thermionic emission when the filament is heated. In a dental x-ray tube, heating the tungsten filament causes electrons to be released from the cathode. These electrons are then accelerated toward the anode by the high tube voltage, forming the cathode rays. They are not protons, neutrons, or photons—the particles that make up cathode rays are electrons. The x-ray photons themselves are produced later when these high-energy electrons interact with the anode target. So the statement correctly identifies cathode rays as electrons produced at the cathode inside an x-ray tube.