Radiation Health and Safety Test Radiation Health and Safety Test Radiation Physics & Principles 1 — Questions and Answers
Question 1: Which type of ionizing radiation has the greatest penetrating power?
- Alpha particles
- Beta particles
- Gamma rays (Correct answer)
- Neutrons
Correct answer: Gamma rays
Gamma rays are highly penetrating electromagnetic radiation that can pass through most materials, requiring dense shielding such as lead or concrete.
Question 2: What is the SI unit of absorbed radiation dose?
- Roentgen
- Rem
- Gray (Correct answer)
- Curie
Correct answer: Gray
The Gray (Gy) is the SI unit of absorbed dose, defined as 1 joule of energy deposited per kilogram of matter.
Question 3: What term describes the time required for a radioactive substance to lose half of its radioactivity?
- Decay constant
- Half-life (Correct answer)
- Mean life
- Biological half-life
Correct answer: Half-life
Half-life is the time it takes for half of the radioactive atoms in a sample to undergo radioactive decay.
Question 4: Which atomic process is responsible for the emission of characteristic X-rays?
- Nuclear fission
- Electron shell transition (Correct answer)
- Neutron capture
- Beta decay
Correct answer: Electron shell transition
Characteristic X-rays are produced when an inner-shell electron vacancy is filled by an outer-shell electron, releasing energy as an X-ray photon.
Question 5: What is Bremsstrahlung radiation?
- Radiation emitted during nuclear fission
- X-rays produced when fast electrons decelerate near a nucleus (Correct answer)
- Gamma rays emitted after beta decay
- Radiation from radioactive decay of heavy elements
Correct answer: X-rays produced when fast electrons decelerate near a nucleus
Bremsstrahlung (braking radiation) is produced when high-energy electrons are decelerated by the electric field of an atomic nucleus, emitting X-ray photons.
Question 6: Which interaction is the predominant photon interaction at diagnostic X-ray energies (20–100 keV)?
- Pair production
- Photoelectric effect
- Compton scattering (Correct answer)
- Coherent scattering
Correct answer: Compton scattering
Compton scattering predominates at diagnostic X-ray energies (roughly 30–150 keV in soft tissue), involving partial energy transfer to a recoil electron with scatter of the photon.
Radiation Health and Safety Test Radiation Health and Safety Test Radiation Physics & Principles 1
Which type of ionizing radiation has the greatest penetrating power?