Exponential Decay - Example
Problem: A radioactive isotope of iodine decays exponentially. There is 50 mg of the element initially, 35 mg after 4 days.
(a) Find a formula of the form
(b) Find the half-life, , of the isotope.
As in every applied problem, first you have to define your variables and their units. Let denote the amount of iodine left, in mg, after time t . Time t is measured in days after the initial moment when we began observing the isotope. To find the formula
describing the amount left as time changes, we need to find the constants and k .