American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

The measurement of the intensity of x- or gamma radiation is best represented by the unit Roentgen per unit of time. This unit provides a direct indication of the radiation exposure in a specific timeframe, helping to quantify how much radiation is present in an environment or how much is being delivered during a radiographic procedure.

Roentgens are a legacy unit that specifically measures the ionization produced in air by x-rays or gamma rays, reflecting the dose of radiation that is accessible to be absorbed by tissues. Using Roentgens per unit of time enables professionals to assess and control radiation exposure during procedures effectively, thereby ensuring safety standards are met.

Other units listed do not appropriately measure intensity in this context: Bequerels measure radioactivity rather than radiation intensity; Gray measures absorbed dose, indicating energy deposited in matter, and Sieverts are used for measuring biological effects of radiation rather than the direct intensity. Therefore, Roentgen per unit of time is the most fitting answer for measuring the intensity of x- or gamma radiation.