What device measures the amount of exposure to radiation for an individual?

The dosimeter is the device specifically designed to measure an individual's exposure to radiation over a period of time. It functions by accumulating and recording the amount of radiation that a person is exposed to, which is crucial for monitoring safety in environments where radiation is present, such as medical facilities or nuclear plants. Dosimeters can come in various forms, including badges, rings, or electronic devices, and their measurements are vital for assessing the risk of radiation exposure to ensure it remains within safe limits.

Other devices mentioned serve different purposes. A radiometer measures the intensity of electromagnetic radiation, such as light, but does not track exposure over time for individuals. A Geiger counter detects and measures ionizing radiation but is more focused on real-time radiation levels in the environment rather than personal exposure. A sonometer, on the other hand, measures sound waves and has no relevance to radiation exposure.