Which statement about characteristic radiation is true?

• A. It arises from electron transitions in the target following inner-shell ionization and contributes a smaller portion relative to bremsstrahlung at typical voltages.
• B. It is the dominant type of radiation at typical tube voltages.
• C. It is produced when electrons decelerate in the target.
• D. It is a type of heat energy.

Answer: (C)

Characterisitic radiation comes from electrons in the target being ionized in an inner shell, followed by an electron from a higher shell filling the vacancy and emitting a photon with a characteristic energy. This yields photons with discrete energies specific to the target material, and these lines are typically a smaller portion of the X-ray output than the bremsstrahlung continuum at common tube voltages. The idea that characteristic radiation is produced by deceleration describes bremsstrahlung, not characteristic lines. And while some energy in the target becomes heat, the emitted photons here are X-rays, not heat energy.