OHST Practice Exam

Which of the following measurements does the inverse square law not apply to?

1. Heat

2. Illumination

3. Noise

4. Radiation

The correct answer is: Noise

The inverse square law is a fundamental principle that describes how the intensity of a physical quantity, such as illumination or radiation, decreases with distance from a point source. This law states that intensity is inversely proportional to the square of the distance from the source. For illumination and radiation, as you move away from the source, the amount of light or radiation received decreases rapidly because the energy spreads out over a larger area. For example, if you double the distance from a light source, the light intensity received decreases to one-quarter of its original value. In the case of heat, while it emanates from a source and can also follow an inverse square relationship under certain conditions (like in radiation heat transfer), it does not solely rely on this relationship when you consider convection and conduction, which can influence heating differently based on the medium. On the other hand, noise does not inherently obey the inverse square law in the same way light or radiation does. Noise levels in a given environment can change due to numerous factors like reflections, environmental conditions, and the nature of sound propagation, leading to a more complex relationship that does not necessarily fit the inverse square framework. Thus, the correct answer is that the inverse square law does not apply to noise, as its intensity