What charge does the Cathode have?

The cathode in a vacuum tube or x-ray tube is the electrode where electrons are emitted and is fundamentally associated with a negative electric charge. This negative charge is essential for the operation of devices like x-ray machines because it serves as a source of electrons, which are then directed towards the anode.

When a high voltage is applied, the cathode heats up, causing thermionic emission where electrons are released from its surface. These electrons, being negatively charged, are then accelerated towards the positively charged anode, where they can collide with target atoms to produce x-rays. Understanding the role of the cathode as negatively charged is crucial in the context of radiation production in dental practices, as it highlights the flow of electrons that facilitates the generation of the x-ray beam.