Exponential Decay

Definition

Exponential decay is a mathematical model that describes the gradual reduction or diminishment of a quantity over time. It is characterized by an initial value that decreases by a constant proportion during each successive time interval, resulting in an exponential decrease. This concept is fundamental to understanding various phenomena in fields such as physics, chemistry, biology, and finance.

5 Must Know Facts For Your Next Test

1. Exponential decay is the inverse of exponential growth, where a quantity decreases by a constant proportion over time.
2. The rate of exponential decay is determined by the decay constant, which is the fraction of the remaining quantity that is lost in each time interval.
3. Exponential decay models are used to describe the behavior of radioactive materials, the cooling of hot objects, the discharge of capacitors, and the growth of bacterial populations.
4. The half-life of a decaying quantity is the time it takes for the quantity to decrease to half of its initial value.
5. Exponential decay curves approach the x-axis as an asymptote, never touching it but getting closer and closer.

Review Questions

• Explain how exponential decay is related to the concept of exponents and scientific notation.
  • Exponential decay is closely tied to the concept of exponents and scientific notation. The mathematical model for exponential decay is an exponential function of the form $f(t) = a \. b^t$, where $a$ is the initial value, $b$ is the decay constant (a value between 0 and 1), and $t$ represents time. The exponent $b^t$ determines the rate at which the quantity decreases over time, exhibiting an exponential pattern. Scientific notation is often used to express very small or very large values associated with exponential decay, as the quantities can change dramatically over time.
• Describe the relationship between exponential decay and the inverse and radical functions.
  • Exponential decay is the inverse of exponential growth, which is closely related to the concept of inverse functions. The inverse of an exponential function is a logarithmic function, and the relationship between these two functions is fundamental to understanding exponential and logarithmic equations. Additionally, the square root function, which is a type of radical function, can be used to calculate the half-life of an exponentially decaying quantity, as the half-life is the time it takes for the quantity to decrease to half of its initial value.
• Analyze how the graph of an exponential decay function can be used to model real-world phenomena and make predictions.
  • The graph of an exponential decay function, which is a downward-sloping curve that approaches the x-axis asymptotically, can be used to model and make predictions about a wide range of real-world phenomena. Examples include the decay of radioactive materials, the cooling of hot objects, the discharge of capacitors, and the growth of bacterial populations. By analyzing the shape of the exponential decay curve and the values of the parameters, such as the initial value and the decay constant, one can make inferences about the underlying processes and make predictions about the future behavior of the system.

Related terms

Exponential Function:

A function of the form $f(x) = a \. b^x$, where $a$ and $b$ are constants, and $b > 0$. Exponential functions exhibit exponential growth or decay depending on the value of $b$.

Half-Life: The time it takes for a quantity to decrease to half of its initial value. Half-life is a key characteristic of exponential decay and is used to measure the rate of decay in various applications.

Asymptote:

A line that a curve approaches but never touches. In the case of exponential decay, the curve approaches the x-axis as an asymptote, never touching it but getting closer and closer.