nic emission: heating a filament until electrons are emitted from its surface.","points":1,"mcqOptions":[{"text":"Thermionic emission: heating a filament until electrons are emitted from its surface.","correct":true,"explanation":"Heating the cathode filament gives electrons enough energy to overcome the metal’s surface barrier, so thermionic emission supplies the electron beam."},{"text":"Photoelectric emission: illuminating a metal surface until photons eject electrons from it.","correct":false,"explanation":"Photoelectric emission requires incident photons to eject electrons. An X-ray tube instead heats its cathode filament, causing thermionic emission from the metal surface."},{"text":"Field emission: applying a strong electric field until electrons escape from its surface.","correct":false,"explanation":"Field emission uses an extremely strong electric field to extract electrons directly. The heated filament in an X-ray tube releases electrons by thermionic emission."},{"text":"Secondary emission: bombarding a metal surface until particles eject electrons from it.","correct":false,"explanation":"Secondary emission occurs when incoming particles knock electrons from a surface. At the cathode, heating the filament releases electrons through thermionic emission."}]},{"id":"f4c93cf9-0c2c-4b4c-952e-ec1a390cb658","cardType":"basic","front":"Why is a vacuum necessary inside an X-ray tube?","back":"To prevent accelerating electrons from colliding with gas molecules and losing kinetic energy.","points":1,"mcqOptions":[{"text":"To prevent accelerating electrons from colliding with gas molecules and losing kinetic energy.","correct":true,"explanation":"A vacuum removes gas molecules from the electrons’ path, allowing them to reach the anode with the kinetic energy gained from the accelerating potential difference."},{"text":"To prevent accelerating electrons from repelling one another and losing kinetic energy.","correct":false,"explanation":"A vacuum does not remove electrostatic repulsion between electrons. It prevents collisions with gas molecules, which would reduce the electrons’ kinetic energy before they reached the anode."},{"text":"To prevent accelerating electrons from being attracted back to the cathode and losing kinetic energy.","correct":false,"explanation":"The applied electric field accelerates electrons away from the cathode. The vacuum is needed to prevent collisions with gas molecules and the resulting loss of kinetic energy."},{"text":"To prevent accelerating electrons from emitting X-rays before reaching the anode and losing kinetic energy.","correct":false,"explanation":"X-rays are produced mainly when electrons are decelerated at the anode target. The vacuum prevents collisions with gas molecules while the electrons are being accelerated."}]},{"id":"45f1c36f-900e-4609-ab79-76f9b2e50e98","cardType":"basic","front":"How is the anode in an X-ray tube protected from melting?","back":"

Made of copper (high thermal conductivity)
The anode rotates to distribute heat
Cooled by circulating oil or water

","points":2,"mcqOptions":[{"text":"

Made of copper (high thermal conductivity)
The anode rotates to distribute heat
Cooled by circulating oil or water

","correct":true,"explanation":"Copper conducts thermal energy away efficiently, rotation spreads energy over a larger target area, and circulating oil or water removes heat from the anode assembly."},{"text":"

Made of lead (high thermal conductivity)
The anode rotates to distribute heat
Cooled by circulating oil or water

","correct":false,"explanation":"Lead is associated with X-ray shielding, not efficient anode cooling. The anode uses copper for high the

Using X-rays

Using X-rays Flashcards

Using X-rays

Using X-rays Flashcards