
Understanding Radioactive Decay
Radioactive decay is a process in which unstable atomic nuclei lose energy through the emission of radiation. This process is characterized by a half-life, which is the time required for half of the radioactive material to decay. The half-life is a constant for each specific radioactive isotope and is typically measured in units of time, such as years or days.
The Half-Life Equation
The equation for radioactive decay is given by:
r=100(21)5d
where r is the amount of radioactive element remaining in a 100mg sample after d days.
Interpreting the Equation
In this equation, the base of the exponent is 21, which represents the fact that the amount of radioactive material decreases by half every 5 days. This is known as the half-life of the radioactive isotope.
Calculating the Daily Percent of Radioactive Decay
To calculate the daily percent of radioactive decay, we need to find the ratio of the amount of radioactive material remaining after one day to the initial amount. This can be done by substituting d=1 into the equation:
r=100(21)51
Simplifying the Equation
To simplify the equation, we can use the fact that (21)51 is equal to (21)51. This can be rewritten as:
r=100(21)51
Evaluating the Expression
To evaluate the expression, we can use a calculator or a computer program to find the value of (21)51. This is approximately equal to 0.8706.
Calculating the Daily Percent of Radioactive Decay
Now that we have the value of (21)51, we can calculate the daily percent of radioactive decay by dividing the amount of radioactive material remaining after one day by the initial amount:
Daily percent of radioactive decay=100100(21)51×100%
Simplifying the Expression
To simplify the expression, we can cancel out the 100 in the numerator and denominator:
Daily percent of radioactive decay=(21)51×100%
Evaluating the Expression
To evaluate the expression, we can multiply the value of (21)51 by 100%:
Daily percent of radioactive decay=0.8706×100%=87.06%
Conclusion
In this article, we have used the half-life equation to calculate the daily percent of radioactive decay for a 100mg sample of radioactive material. We have shown that the daily percent of radioactive decay is approximately 87.06%.
References
Appendix
Derivation of the Half-Life Equation
The half-life equation can be derived from the following assumptions:
- The amount of radioactive material remaining after a certain time is proportional to the initial amount.
- The rate of radioactive decay is constant.
Using these assumptions, we can derive the half-life equation as follows:
Let N(t) be the amount of radioactive material remaining after time t. Then, we can write:
N(t)=N0e−λt
where N0 is the initial amount of radioactive material, λ is the decay constant, and t is time.
The half-life equation can be obtained by substituting t=t1/2 into the above equation, where t1/2 is the half-life:
N(t1/2)=N0e−λt1/2
Since N(t1/2)=21N0, we can write:
21N0=N0e−λt1/2
Dividing both sides by N0, we get:
21=e−λt1/2
Taking the natural logarithm of both sides, we get:
ln21=−λt1/2
Solving for λ, we get:
λ=−t1/2ln21
Substituting this expression for λ into the half-life equation, we get:
N(t)=N0e−t1/2ln21t
Simplifying this expression, we get:
N(t)=N0(21)t1/2t
This is the half-life equation.
Derivation of the Daily Percent of Radioactive Decay
To derive the daily percent of radioactive decay, we can use the half-life equation:
N(t)=N0(21)t1/2t
Substituting t=1 day into this equation, we get:
N(1)=N0(21)t1/21
Since t1/2=5 days, we can write:
N(1)=N0(21)51
Dividing both sides by N0, we get:
N0N(1)=(21)51
Multiplying both sides by 100%, we get:
Daily percent of radioactive decay=(21)51×100%
Evaluating this expression, we get:
\text{Daily percent of radioactive decay} = 0.8706 \times 100\% = 87.06\%$<br/>
**The Half-Life Equation and Daily Radioactive Decay: Q&A**
=====================================================
Q: What is the half-life equation?

A: The half-life equation is a mathematical formula that describes the rate of radioactive decay of a substance. It is given by:
r=100(21)5d</span></p><p>where<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>r</mi></mrow><annotationencoding="application/x−tex">r</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.4306em;"></span><spanclass="mordmathnormal"style="margin−right:0.02778em;">r</span></span></span></span>istheamountofradioactiveelementremainingina<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>100</mn><mtext> </mtext><mtext>mg</mtext></mrow><annotationencoding="application/x−tex">100mg</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8389em;vertical−align:−0.1944em;"></span><spanclass="mord">100</span><spanclass="mspace"style="margin−right:0.1667em;"></span><spanclass="mordtext"><spanclass="mord">mg</span></span></span></span></span>sampleafter<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>d</mi></mrow><annotationencoding="application/x−tex">d</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.6944em;"></span><spanclass="mordmathnormal">d</span></span></span></span>days.</p><h2><strong>Q:Whatisthesignificanceofthehalf−lifeequation?</strong></h2><p>A:Thehalf−lifeequationissignificantbecauseitallowsustocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftime.Thisisusefulinavarietyofapplications,includingnuclearmedicine,geology,andenvironmentalscience.</p><h2><strong>Q:HowdoIcalculatethedailypercentofradioactivedecay?</strong></h2><p>A:Tocalculatethedailypercentofradioactivedecay,youcanusethefollowingformula:</p><pclass=′katex−block′><spanclass="katex−display"><spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"display="block"><semantics><mrow><mtext>Daily percent of radioactive decay</mtext><mo>=</mo><msup><mrow><mofence="true">(</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mofence="true">)</mo></mrow><mfrac><mn>1</mn><mn>5</mn></mfrac></msup><mo>×</mo><mn>100</mn><mimathvariant="normal"></annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8889em;vertical−align:−0.1944em;"></span><spanclass="mordtext"><spanclass="mord">Daily percent of radioactive decay</span></span><spanclass="mspace"style="margin−right:0.2778em;"></span><spanclass="mrel">=</span><spanclass="mspace"style="margin−right:0.2778em;"></span></span><spanclass="base"><spanclass="strut"style="height:2.744em;vertical−align:−0.95em;"></span><spanclass="minner"><spanclass="minner"><spanclass="mopendelimcenter"style="top:0em;"><spanclass="delimsizingsize3">(</span></span><spanclass="mord"><spanclass="mopennulldelimiter"></span><spanclass="mfrac"><spanclass="vlist−tvlist−t2"><spanclass="vlist−r"><spanclass="vlist"style="height:1.3214em;"><spanstyle="top:−2.314em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="mord"><spanclass="mord">2</span></span></span><spanstyle="top:−3.23em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="frac−line"style="border−bottom−width:0.04em;"></span></span><spanstyle="top:−3.677em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="mord"><spanclass="mord">1</span></span></span></span><spanclass="vlist−s"></span></span><spanclass="vlist−r"><spanclass="vlist"style="height:0.686em;"><span></span></span></span></span></span><spanclass="mclosenulldelimiter"></span></span><spanclass="mclosedelimcenter"style="top:0em;"><spanclass="delimsizingsize3">)</span></span></span><spanclass="msupsub"><spanclass="vlist−t"><spanclass="vlist−r"><spanclass="vlist"style="height:1.7939em;"><spanstyle="top:−4.2029em;margin−right:0.05em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size6size3mtight"><spanclass="mordmtight"><spanclass="mordmtight"><spanclass="mopennulldelimitersizingreset−size3size6"></span><spanclass="mfrac"><spanclass="vlist−tvlist−t2"><spanclass="vlist−r"><spanclass="vlist"style="height:0.8443em;"><spanstyle="top:−2.656em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size3size1mtight"><spanclass="mordmtight"><spanclass="mordmtight">5</span></span></span></span><spanstyle="top:−3.2255em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="frac−linemtight"style="border−bottom−width:0.049em;"></span></span><spanstyle="top:−3.384em;"><spanclass="pstrut"style="height:3em;"></span><spanclass="sizingreset−size3size1mtight"><spanclass="mordmtight"><spanclass="mordmtight">1</span></span></span></span></span><spanclass="vlist−s"></span></span><spanclass="vlist−r"><spanclass="vlist"style="height:0.344em;"><span></span></span></span></span></span><spanclass="mclosenulldelimitersizingreset−size3size6"></span></span></span></span></span></span></span></span></span></span><spanclass="mspace"style="margin−right:0.2222em;"></span><spanclass="mbin">×</span><spanclass="mspace"style="margin−right:0.2222em;"></span></span><spanclass="base"><spanclass="strut"style="height:0.8056em;vertical−align:−0.0556em;"></span><spanclass="mord">100<p>Thisformulaisderivedfromthehalf−lifeequationandtakesintoaccountthefactthattheamountofradioactivematerialdecreasesbyhalfevery5days.</p><h2><strong>Q:Whatisthedailypercentofradioactivedecayfora<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>100</mn><mtext> </mtext><mtext>mg</mtext></mrow><annotationencoding="application/x−tex">100mg</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8389em;vertical−align:−0.1944em;"></span><spanclass="mord">100</span><spanclass="mspace"style="margin−right:0.1667em;"></span><spanclass="mordtext"><spanclass="mord">mg</span></span></span></span></span>sampleofradioactivematerial?</strong></h2><p>A:Thedailypercentofradioactivedecayfora<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>100</mn><mtext> </mtext><mtext>mg</mtext></mrow><annotationencoding="application/x−tex">100mg</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8389em;vertical−align:−0.1944em;"></span><spanclass="mord">100</span><spanclass="mspace"style="margin−right:0.1667em;"></span><spanclass="mordtext"><spanclass="mord">mg</span></span></span></span></span>sampleofradioactivematerialisapproximately<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>87.06</mn><mimathvariant="normal"><h2><strong>Q:Howdoesthehalf−lifeequationrelatetotheconceptofhalf−life?</strong></h2><p>A:Thehalf−lifeequationiscloselyrelatedtotheconceptofhalf−life.Thehalf−lifeofaradioactivesubstanceisthetimeittakesforhalfoftheoriginalamountofthesubstancetodecay.Thehalf−lifeequationtakesintoaccountthisconceptandallowsustocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftime.</p><h2><strong>Q:CanIusethehalf−lifeequationtocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftime?</strong></h2><p>A:Yes,youcanusethehalf−lifeequationtocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftime.Simplysubstitutethedesiredtimeintotheequationandsolvefortheamountofradioactivematerialremaining.</p><h2><strong>Q:Whataresomecommonapplicationsofthehalf−lifeequation?</strong></h2><p>A:Thehalf−lifeequationhasavarietyofapplicationsinfieldssuchasnuclearmedicine,geology,andenvironmentalscience.Somecommonapplicationsinclude:</p><ul><li>Calculatingtheamountofradioactivematerialremaininginasampleafteracertainperiodoftime</li><li>Determiningthehalf−lifeofaradioactivesubstance</li><li>Modelingthedecayofradioactivematerialsintheenvironment</li><li>Calculatingthedoseofradiationreceivedbyapatientinanuclearmedicineprocedure</li></ul><h2><strong>Q:CanIusethehalf−lifeequationtocalculatethedailypercentofradioactivedecayforasampleofradioactivematerialwithadifferentinitialamount?</strong></h2><p>A:Yes,youcanusethehalf−lifeequationtocalculatethedailypercentofradioactivedecayforasampleofradioactivematerialwithadifferentinitialamount.Simplysubstitutethedesiredinitialamountintotheequationandsolveforthedailypercentofradioactivedecay.</p><h2><strong>Q:Whataresomelimitationsofthehalf−lifeequation?</strong></h2><p>A:Thehalf−lifeequationhasseverallimitations,including:</p><ul><li>Itassumesthattherateofradioactivedecayisconstantovertime</li><li>Itassumesthattheamountofradioactivematerialremaininginasampleisdirectlyproportionaltotheinitialamount</li><li>Itdoesnottakeintoaccounttheeffectsofexternalfactors,suchastemperatureandpressure,ontherateofradioactivedecay</li></ul><h2><strong>Q:CanIusethehalf−lifeequationtocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftimeifthesampleisnota<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>100</mn><mtext> </mtext><mtext>mg</mtext></mrow><annotationencoding="application/x−tex">100mg</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8389em;vertical−align:−0.1944em;"></span><spanclass="mord">100</span><spanclass="mspace"style="margin−right:0.1667em;"></span><spanclass="mordtext"><spanclass="mord">mg</span></span></span></span></span>sample?</strong></h2><p>A:Yes,youcanusethehalf−lifeequationtocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftimeifthesampleisnota<spanclass="katex"><spanclass="katex−mathml"><mathxmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mn>100</mn><mtext> </mtext><mtext>mg</mtext></mrow><annotationencoding="application/x−tex">100mg</annotation></semantics></math></span><spanclass="katex−html"aria−hidden="true"><spanclass="base"><spanclass="strut"style="height:0.8389em;vertical−align:−0.1944em;"></span><spanclass="mord">100</span><spanclass="mspace"style="margin−right:0.1667em;"></span><spanclass="mordtext"><spanclass="mord">mg</span></span></span></span></span>sample.Simplysubstitutethedesiredinitialamountintotheequationandsolvefortheamountofradioactivematerialremaining.</p><h2><strong>Q:Whataresomecommonmistakestoavoidwhenusingthehalf−lifeequation?</strong></h2><p>A:Somecommonmistakestoavoidwhenusingthehalf−lifeequationinclude:</p><ul><li>Failingtoaccountfortheeffectsofexternalfactors,suchastemperatureandpressure,ontherateofradioactivedecay</li><li>Usingthehalf−lifeequationtocalculatetheamountofradioactivematerialremaininginasampleafteracertainperiodoftimewithouttakingintoaccounttheinitialamountofthesample</li><li>Failingtousethecorrectunitswhensubstitutingvaluesintotheequation</li></ul><h2><strong>Q:CanIusethehalf−lifeequationtocalculatethedailypercentofradioactivedecayforasampleofradioactivematerialwithadifferenthalf−life?</strong></h2><p>A:Yes,youcanusethehalf−lifeequationtocalculatethedailypercentofradioactivedecayforasampleofradioactivematerialwithadifferenthalf−life.Simplysubstitutethedesiredhalf−lifeintotheequationandsolveforthedailypercentofradioactivedecay.</p><h2><strong>Q:Whataresomeresourcesavailableforlearningmoreaboutthehalf−lifeequationanditsapplications?</strong></h2><p>A:Someresourcesavailableforlearningmoreaboutthehalf−lifeequationanditsapplicationsinclude:</p><ul><li>Textbooksonnuclearphysicsandradiationsafety</li><li>Onlinecoursesandtutorialsonnuclearphysicsandradiationsafety</li><li>Professionalorganizations,suchastheAmericanNuclearSocietyandtheInternationalAtomicEnergyAgency</li><li>Researcharticlesandpapersonthehalf−lifeequationanditsapplications</li></ul>