If you double the distance from a radiation source, how will the intensity of radiation change?

Doubling the distance from a radiation source causes the intensity of radiation to decrease according to the inverse square law. This law states that the intensity of radiation is inversely proportional to the square of the distance from the source. Therefore, if the distance is doubled, the intensity of radiation decreases by a factor of the square of two, which is four.

In practical terms, if you start at a distance of one meter from a source, the radiation intensity would be measured at a certain level. When you increase the distance to two meters, the new intensity will be one-fourth of the original intensity. This principle is critical in radiation protection practices, as increasing distance from a radiation source is a common method to reduce exposure levels. Hence, the correct response indicates that the radiation intensity decreases by a factor of four when the distance is doubled.