For a particular target element, the K-shell binding energy is 69.5 keV. Electrons accelerated in an X-ray tube are used to create K-shell vacancies so that characteristic K-series radiation can be emitted. Ideally, what is the minimum accelerating potential required before K-series characteristic X-rays can appear?
Options

Question

For a particular target element, the K-shell binding energy is 69.5 keV. Electrons accelerated in an X-ray tube are used to create K-shell vacancies so that characteristic K-series radiation can be emitted. Ideally, what is the minimum accelerating potential required before K-series characteristic X-rays can appear?

Options

G1 Physics · Accepted Answer

To produce a characteristic K-series photon, a vacancy must first be created in the K-shell. Therefore an incident electron must have at least the K-shell binding energy: K(electron) ≥ 69.5 keV. Since an electron accelerated through V kilovolts gains V keV of kinetic energy, V(min) = 69.5 kV. Correct option: B.