What type of current is required for proper operation of the x-ray tube?

• A. Direct
• B. Falling load
• C. Alternating
• D. Fluctuating

Answer: (A)

X-ray tubes must have a unidirectional potential across them so electrons flow steadily from the heated filament (cathode) toward the anode. This steady, single-direction current (direct current) keeps the emission and acceleration of electrons consistent, producing a stable X-ray beam. If the supply were alternating current, the voltage would reverse every half-cycle, stopping or reversing electron flow and causing unstable exposure, reduced efficiency, and potential damage. In practice, x-ray generators rectify AC to provide direct current (often pulsed DC) to the tube for reliable operation.