ARRT Practice Exam 2025 – All-in-One Guide to Master Your Radiologic Technologist Certification

The inverse square law describes how the intensity of radiation or sound waves diminishes as the distance from the source increases. Specifically, it states that the intensity is inversely proportional to the square of the distance from the source. The correct formula, which involves comparing two points of intensity and distance, is I1 / I2 = D2 squared / D1 squared.

In this formula, I1 represents the intensity at the first distance (D1), and I2 represents the intensity at the second distance (D2). The relationship indicated by this equation highlights that if the distance from the source is doubled, the intensity will decrease to one-fourth of the original intensity. This is because intensity decreases with the square of the distance change, which is a fundamental concept in physics, particularly in radiology. Understanding this principle is vital for radiologic technologists, as it impacts dose management and patient safety during imaging procedures. The formula effectively allows for calculations when comparing different distances from a radiation source, which is essential for accurate assessments and maintaining safe practice standards.