If the exposure rate to an individual standing 7.0 feet from a source of radiation is 0.5 mgy/hr, what will be the dose received after 20 minutes at a distance of 3.0 feet from the source?

0.389mGy

Explanation:

You can simply use variation to get the answer. if at 7 feet, the exposure rate is 0.5mGy/hr. Then at 1 feet, the exposure rate would be higher because the rate at which you are exposed to radiation is inversely proportional to the distance you are from the source. i.e the smaller the distance the higher the rate of exposure.

But the question is what will be the dose exposed to after 20 minutes at a distance of 3.0 feet from the source?

we calculate as follow

b would be the answer

c. magnitude and direction