Final answer:
A 1 roentgen is a unit of measure for radiation exposure in air, defined as the amount of radiation that produces an electrical charge of 2.58 x 10^-4 C in 1 kg of dry air, and not the energy absorbed by biological tissue.
Step-by-step explanation:
The term 1 roentgen refers to a unit that measures the quantity of radiation exposure in air. It is defined as the amount of radiation needed to produce an electrical charge of 2.58 × 10-4 C in 1 kg of dry air. The unit is named after Wilhelm Röntgen, the discoverer of X-rays. The roentgen is related to but different from the units that measure radiation effects on biological tissues, like the rad (radiation absorbed dose) and the gray (Gy), which define the amount of energy absorbed by a material or tissue. While roentgen measures the radiation exposure in air, it is not a direct measure of the impact on biological tissue, which is typically measured in rad or Gy. Specifically, 1 rad is equal to the amount of radiation that causes 0.01 J of energy to be absorbed by 1 kg of matter, and 1 Gy is equal to the absorption of 1 J of energy per kilogram.