PRACTICE QUESTIONS AND CORRECT
ANSWERS|100% CORRECT PASS|2026 UPDATE
1. What is the fundamental definition of ionizing radiation?
a) Energy that only causes heating of materials
b) Energy in transit, either as particles or electromagnetic waves, that has enough energy to
remove orbital electrons from atoms
c) Visible light emitted from radioactive materials
d) Sound waves produced by nuclear reactions
Answer: b
Rationale: Ionizing radiation is specifically defined as radiation with sufficient energy to ionize
matter—meaning it can remove electrons from atoms, creating ions. This ionization process is
what causes biological damage. Option a describes nonionizing radiation effects, c is incorrect
as visible light is nonionizing, and d refers to acoustic phenomena unrelated to radiation.
2. What is an isotope?
a) An atom with a different number of protons
b) Atoms with the same atomic number but different mass numbers
c) A type of radiation shielding material
d) A device used to measure radiation
,Answer: b
Rationale: Isotopes are variants of a particular chemical element that have the same number of
protons (same atomic number) but different numbers of neutrons, resulting in different mass
numbers. They may be stable or unstable (radioactive). Options a, c, and d are incorrect as they
describe different elements, shielding, and detection equipment respectively.
3. Which two types of electromagnetic radiation are primarily used for industrial radiography?
a) Xrays and Microwaves
b) Gamma and Xrays
c) Infrared and UV
d) Radio waves and visible light
Answer: b
Rationale: Both gamma rays (emitted from radioactive isotopes like Iridium192 or Cobalt60) and
Xrays (produced by Xray machines) are forms of electromagnetic radiation with short
wavelengths and high energy, allowing them to penetrate materials for nondestructive testing.
The other options are nonionizing radiation forms not used for industrial radiography.
4. What is the primary difference between Xrays and gamma rays?
a) Gamma rays travel faster
b) Xrays have more penetrating power
c) The source of radiation
,d) Gamma rays are not dangerous
Answer: c
Rationale: Xrays and gamma rays are identical in nature and properties. The only fundamental
difference is their origin: Xrays are produced extranuclearly (when electrons interact outside the
nucleus), while gamma rays originate from the nucleus of radioactive atoms during decay.
5. Which of the following is an example of nonionizing radiation?
a) Gamma rays from Cobalt60
b) Alpha particles
c) Visible light
d) Xrays
Answer: c
Rationale: Nonionizing radiation includes the electromagnetic spectrum with insufficient energy
to cause ionization, such as visible light, radio waves, microwaves, and infrared radiation. Alpha
particles, gamma rays, and Xrays all have ionizing capabilities.
6. What process results in the formation of ion pairs?
a) Excitation
b) Ionization
, c) Fusion
d) Attenuation
Answer: b
Rationale: Ionization is the specific process where radiation has enough energy to remove an
orbital electron from an atom, creating a positively charged ion and a negatively charged free
electron (an ion pair). Excitation involves raising an electron to a higher energy level without
ejection, while fusion and attenuation are different nuclear and interaction processes.
7. What is the unit of radioactivity (quantity of radioactive material)?
a) Roentgen
b) Rem
c) Curie or Becquerel
d) Rad
Answer: c
Rationale: The Curie (Ci) and the Becquerel (Bq) are units that measure the activity of a
radioactive material—the rate at which atoms decay. The Roentgen measures exposure in air,
the Rad measures absorbed dose, and the Rem measures dose equivalent (biological
effectiveness).
8. The term "HalfLife" refers to: