The concept of light taking the path of least resistance is not a precise scientific definition, but rather a way of explaining the behavior of light in certain situations using an intuitive analogy.
In simple terms, the phrase "path of least resistance" suggests that light tends to follow the easiest or most direct path when propagating through a medium. This idea is often used to describe the behavior of light when it encounters different mediums with varying refractive indices, such as when it passes from one medium to another (e.g., from air to water or from air to glass).
According to Fermat's principle of least time, which is a fundamental principle in optics, light tends to travel along a path that minimizes the travel time between two points. In the case of different mediums, light tends to change its direction or bend when it encounters a boundary between two mediums with different refractive indices. This bending of light is known as refraction.
The path that light takes when it undergoes refraction is determined by Snell's law, which describes the relationship between the incident angle of light, the refractive indices of the two mediums, and the angles of refraction. Snell's law allows us to calculate the angle of refraction based on the incident angle and refractive indices.
While the concept of the path of least resistance can be a helpful way to understand certain aspects of light's behavior, it's important to note that light actually follows the laws of physics and interacts with the electromagnetic field and matter in a complex manner. So, the behavior of light is ultimately determined by the fundamental principles of optics, such as Fermat's principle and Snell's law, rather than a literal notion of resistance.