A particular smoke detector contains 2.85 uCI of 241Am , with a half-life of 458 . The isotope is encased in a thin aluminum container. Calculate the mass of 241Am in grams in the detector. Fears of radiation exposure from normal use of such detectors are largely unfounded. Identify reasons why 241Am smoke detectors are perfectly safe. The amount of americium is very little. The detector is housed in an aluminum case. Ions get trapped by electrodes. The penetrating power of radiation is limited. The detector has a plastic cover. The number of particles leaving the case is low.