Distinguish between passive and active dosimetry and give examples.

• A. Passive dosimetry records dose without power (film badge, TLD); active dosimetry provides real-time readouts and alarms (electronic dosimeters).
• B. Passive dosimetry uses electronic alarms; active uses film.
• C. Passive dosimetry is for gamma only; active for neutrons.
• D. Passive dosimetry requires power; active does not.

Answer: (A)

The key idea is that one type records exposure over time and is read later, while the other continuously monitors and displays dose during exposure. Passive dosimetry uses detectors that store information about the radiation dose without needing power to operate during the exposure. After a period of use, the detector is read out to determine the dose. Examples include film badges and thermoluminescent dosimeters (TLDs). Active dosimetry, on the other hand, provides real-time readouts and often alarms if dose or dose rate exceeds a threshold, because it requires power to continuously monitor and display the dose. Examples are electronic personal dosimeters and pocket dosimeters with real-time readouts.

The other statements mix up these roles or overgeneralize about radiation types or power needs: active devices aren’t simply “films” and passive devices aren’t powered during exposure; both types can measure more than one radiation type, and the main distinction is real-time readout versus post-exposure recording.