31.5 Exercise 26

Data from the appendices and the periodic table may be needed for these problems.

(a) The $^{\text{210}} \text{Po}$ source used in a physics laboratory is labeled as having an activity of $1.0 \mu \text{Ci}$ on the date it was prepared. A student measures the radioactivity of this source with a Geiger counter and observes 1500 counts per minute. She notices that the source was prepared 120 days before her lab. What fraction of the decays is she observing with her apparatus? (b) Identify some of the reasons that only a fraction of the $\alpha$ s emitted are observed by the detector.