Bremsstrahlung photons are produced when fast electrons are decelerated by the Coulomb field of nuclei.

• A. Deflection by electrons
• B. Electron capture by nucleus
• C. Deceleration in the nuclear field
• D. Ionization of atoms

Answer: (C)

Bremsstrahlung arises when a fast electron is slowed down by the electric (Coulomb) field of a nucleus as it passes near it. That deceleration (change in velocity) of the charged particle causes the emission of a photon, producing the continuous X-ray spectrum. This is why the statement describing deceleration in the nuclear field is the best answer.

Deflection by electrons involves scattering off other electrons, not the nucleus, so it isn’t the mechanism behind bremsstrahlung. Electron capture by the nucleus is a nuclear process that changes the nucleus and emits other radiation, not the continuous braking radiation. Ionization of atoms removes electrons and can produce other photons in different contexts, but bremsstrahlung specifically comes from the deceleration in the nuclear Coulomb field.