Physics Laboratory Experiments

Jerry D. Wilson, Cecilia A. Hernandez-Hall

Chapter 37 Radioactive Half-Life - all with Video Answers

Educators

Chapter Questions

Problem 1

In the experiment, if the Ba- $137 \mathrm{~m}$ sample were placed closer to the Geiger tube, the measured activity would be greater (inverse-square relationship). Would this affect the result of the half-life? Explain how this would affect the $N$ -versus- $t$ graph on Cartesian graph paper (or on semi-log paper).

Lainey Roebuck

Numerade Educator

01:52

Problem 2

A cobalt-60 source has a measured activity of $12,000 \mathrm{cpm}$. After how long would the observed activity be $750 \mathrm{cpm} ?$ (The half-life of $\operatorname{Co}-60$ is $5.27$ years.)

Arron Martel

Numerade Educator

03:51

Problem 3

An instructor buys a $10-\mu \mathrm{Ci} \mathrm{Cs}-137$ source for laboratory experiments. After 5 years, what is (a) the strength of the source in $\mu \mathrm{Ci} ;$ (b) the activity of the source in disintegrations per second? $\left(1 \mathrm{Ci}=3.70 \times 10^{10}\right.$ disintegrations/s.) (c) What is the strength of the source in becquerels (Bq)? (The becquerel is the official SI unit: $1 \mathrm{Ci}=3.7 \times 10^{10} \mathrm{~Bq}$.)

Ren Jie Tuieng

Numerade Educator

01:53

Problem 4

Cesium-136 is also radioactive and decays into barium-136. Write the nuclear equation for this reaction.

Jennifer Hudspeth

Numerade Educator