# Inverse Square Law Equation - Video Lesson

This lesson is about the inverse square law. Remember that the inverse square law is commonly used in radiography and in radiation physics to describe how the ray beam changes when the distance changes. The inverse square law is actually described by this formula. This is the most common representation of the inverse where law formula, but I personally don't find it, especially helpful. It's not easy. It's not practical for use. And so the second formula I personally recommend when using the inverse square law to solve particular equations. I, two, which is the intensity, is equal to the first intensity multiplied by a ratio of the squared distances. And for this more practical formula, I two is equal to I one multiplied by d one squared over d two squared. And so this is just a simple derivative of the initial equation, which I personally find easier to use. The I in this equation obviously refers to intensity, the d refers to distance, distance as in the distance

## Lesson Quiz

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