Dental Assistant Practice Exam

What charge does the cathode have in a dental x-ray tube?

1. Positive charge

2. Neutral charge

3. Negative charge

4. Varied charge

The correct answer is: Negative charge

In a dental x-ray tube, the cathode is negatively charged. The cathode is essential for generating x-rays as it emits electrons when heated. This process occurs in a filament found in the cathode assembly. When you apply a high voltage across the tube, the electrons emitted from the cathode are attracted toward the anode, which is positively charged. As these electrons accelerate toward the anode, they can collide with the anode material and generate x-rays as a result of these interactions. The negative charge of the cathode is crucial for the functioning of the x-ray tube, as it establishes the flow of electrons necessary for x-ray production. The other charge options are not applicable in this context. A positive charge denotes the anode, a neutral charge would not facilitate electron flow, and a varied charge is not characteristic of the cathode in a stable x-ray tube operation.