Which component is heated to emit electrons in the x-ray tube?

Which component is heated to emit electrons in the x-ray tube?

• A. Anode
• B. Filament within the cathode
• C. Target
• D. Vacuum tube walls

Answer: (B)

The main idea is thermionic emission from a heated filament in the cathode. In an x-ray tube, electrons are produced when the filament inside the cathode is heated; this heat gives surface electrons enough energy to overcome the work function, causing them to be emitted into the tube’s vacuum. Those electrons are then pulled toward the anode by the high-voltage potential and produce x-rays when they strike the target. The other parts don’t emit electrons in normal operation: the anode serves as the target that the electrons hit to generate x-rays; the actual material where the x-ray production occurs is the target, located on the anode; the vacuum tube walls simply enclose the tube and maintain the vacuum—no electron emission happens there.

The main idea is thermionic emission from a heated filament in the cathode. In an x-ray tube, electrons are produced when the filament inside the cathode is heated; this heat gives surface electrons enough energy to overcome the work function, causing them to be emitted into the tube’s vacuum. Those electrons are then pulled toward the anode by the high-voltage potential and produce x-rays when they strike the target.

The other parts don’t emit electrons in normal operation: the anode serves as the target that the electrons hit to generate x-rays; the actual material where the x-ray production occurs is the target, located on the anode; the vacuum tube walls simply enclose the tube and maintain the vacuum—no electron emission happens there.