Some smoke detectors (see the figure below) use the radiation produced by the decay of 241 95 Am (half-life 432 yr) to ionize air molecules, which in turn produces a steady current across two electrodes. If smoke enters the region of ionization, the alpha particles are absorbed by the smoke particulates, reducing the current across the electrodes. The electronic circuitry then sounds the alarm when it senses any current reduction. How long does it take for the activity of 241 95 Am to drop to 3.4% of its initial value?
yr
activity of a sample is given by
= 0.693/T(1/2) = 1.6 x 10-3 per year
A= 3.4/100Ao
plugging in the values we get
t =2113.37 years
Some smoke detectors (see the figure below) use the radiation produced by the decay of 241...
Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take in years for 44.0 % of an Am-241 sample to decay?
Americium-241 is used in some smoke detectors. It is an alpha emitter with a half-life of 432 years. How long will it take in years for 32.0 % of an Am-241 sample to decay? Express your answer numerically in years.
1. Smoke detectors use Am-241, an alpha emitter, to detect smoke particles. A parent is concerned that having a smoke detector may expose their child to radioactivity. Which explanation most accurately addresses this concern? a Concern is justified since inhaling even small amounts of alpha particles is bad. b Smoke inhalation risk is immediate and cancer risk from radiation long-term. c If the detector is on the ceiling, the radioactivity exposure is minimal. d Alpha particles don't travel far and...
<Chapter 20 practice for Quiz 12 on 23 April Smoke Detectors and Radioactive Isotopes ® 18 of 28 > 1 Review | Constants Periodic Table Part A A particular smoke detector contains 1.35 uCi of 241 Am, with a half-life of 458 years. The isotope is encased in a thin aluminum container. Calculate the mass of 241 Am in grams in the detector. Americium is used in household smoke detectors as a source of a particles. The device actually responds...
Americium is used in household smoke detectors as a source of ? particles. The device actually responds to the presence of ions from a fire, rather than responding to smoke. A schematic is shown in the image. (Figure 1) The entire setup is enclosed in the familiar plastic housing. The 241Am, which is an ?-emitter, is encased in an aluminum container with an opening that aims the ? particles through an air gap between electrically charged plates. The ? particles...