In an X-ray tube, electrons are emitted from which component?

Question

Question

Answer 1

Correct Answer: Cathode

Rationale:

In an X-ray tube, the cathode is a crucial component responsible for the emission of electrons. The cathode typically consists of a filament which, when heated, releases electrons through a process known as thermionic emission.
The heated filament in the cathode provides the necessary energy for electrons to overcome the material's work function and be emitted into the vacuum of the X-ray tube.
These emitted electrons are then accelerated towards the anode by a high-voltage difference applied between the cathode and the anode, creating the electron stream necessary for X-ray production.

Explanation of Other Options:

Anode

Rationale: The anode in an X-ray tube serves as the target for the accelerated electrons emitted from the cathode. It is not responsible for emitting electrons but rather for interacting with them to produce X-rays.

Filament

Rationale: While the filament is indeed part of the cathode assembly and is responsible for the thermionic emission of electrons, it is not an independent component from the cathode. Therefore, the correct answer remains the cathode, which includes the filament.

Target

Rationale: The target, also known as the anode target, is the specific area on the anode where the high-speed electrons collide. This collision results in the production of X-rays. The target itself does not emit electrons; it is where the X-rays are generated.

Conclusion:

The cathode in an X-ray tube is the component that emits electrons through the process of thermionic emission. The anode serves as the target for these electrons to generate X-rays. The filament is part of the cathode assembly, and the target is part of the anode. Understanding the roles of these components is crucial for comprehending the operation of an X-ray tube.