Question

The unit of Radiation exposure is?

Answer 1

Radiation is the energy travelling as waves or particles. We measure general two phenomena when we discuss radiation. One is ‘activity’ and another one is ‘Exposure’. Here exposure defines the amount of radiation travelling through the air and activity shows how much radiation coming out from particles.

Complete answer:
Radiation exposure is expressed in several ways to account for the different levels of harms caused by the different forms of radiation and different sensitivity of tissue.
Exposure (Absorbed dose)
Radiation exposure is measured by an international (SI) unit called the gray (Gy) or the conventional unit ‘rad’.
The radiation exposure is equivalent to energy deposited in a kilogram of a substance by the radiation. The important concept is that exposure is measured by what radiation of substance. Not particularly about radiation. This allows us for different types of radiation that are particles and waves.
Effective Dose:
The probability of a harmful effect from radiation exposure depends on the parts of the body that are exposed. Some parts are more sensitive to radiation than others. When an equivalent dose is multiplied by the tissue weighting factor of the organ that is equivalent to effective dose. The unit of effective dose is Sievert (Sv)

Note:
For practical purpose 1R (exposure) = 1rad (absorbed dose) =1rem 9dose equivalent). The measure in a rem tells the amount of energy that a radioactive source deposited in living tissue.