Exponential decay: Half-life

Exponential decay: Half-life

In the field of nuclear physics, half-life refers to the amount of time required for radioactive substances to decay into half. In this lesson, we will work on word questions about exponential decay of radioactive substances.
Basic concepts: Solving exponential equations with logarithms, Solving logarithmic equations,
Related concepts: Derivative of inverse trigonometric functions, Derivative of logarithmic functions,

Lessons

exponential growth/decay: Af=Ai(f)timeperiod { A_f = A_i (f)^{time\over period}}

Af {A_f} : final amount
Ai {A_i} : initial amount
f {f }
: growth/decay factor
half-time→f=12 \to f = {1\over 2}
triple
→f=3\to f = {3}
ten-fold
→f=10 \to f = {10}
increase by 10%→f=(1+10100)=1.1 \to f = {({1 + {10\over 100}}) } { = 1.1}
decrease by 8%→f=(1−8100)=0.92 \to f = {({1 - {8\over 100}}) } { = 0.92}
time {time} : total time given
period {period} : every length of time
  • 1.
    half-life decay

    Strontium-90 is a radioactive substance with a half-life of 28 days.
    How many days will it take for a 200 gram sample of strontium-90 to be
    reduced to 8 grams?

Do better in math today
Get Started Now
21.
Applications of Exponential Functions
21.1
Exponential growth and decay by a factor
21.2
Exponential decay: Half-life
21.3
Exponential growth and decay by percentage
21.4
Finance: Compound interest
21.5
Continuous growth and decay
AU Maths Methods
Don't just watch, practice makes perfect.