When the angle at which light strikes the cladding is low enough, what occurs when all of the light is reflected back into the core?

Total Internal Reflection occurs when light travels from a medium with a higher refractive index (like the core of a fiber optic) to a medium with a lower refractive index (like the cladding) at an angle that exceeds the critical angle. At this point, rather than passing into the cladding, all of the light is reflected back into the core.

This phenomenon is essential in fiber optics, as it allows light signals to travel great distances with minimal loss, making it a fundamental principle for the technology used in telecommunications and data transmission. Understanding total internal reflection helps grasp how fiber optics create clear and efficient communication pathways by keeping the light within the core.