This kind of reflection is called “internal reflection.” For TIR, the critical incident angle is θ c, the exit angle will approach 90° the total internal reflection will occur for the angle of incidence higher than the critical angle. When a light ray reaches a medium with a lower index of refraction, it bends away from the normal and comes back, resulting in an exit angle higher than that of the incident angle. Total Internal Reflection Equation and Formula The angle of incidence should be higher than the critical angle, as defined by Snell’s law. The light ray must be moving from a denser medium to a rarer medium that is, the first medium’s refractive index must be greater than the second medium’s. TIR exists only when the following two criteria are satisfied: Total internal reflection (TIR) occurs when all incidents’ light is reflected off a barrier. The Prerequisites For Total Internal Reflection TIR will not occur if such angle of incidence equals to or less than the critical angle. Total internal reflection happens when the incidence angle exceeds critical angle. This is when the light is reflected by a transparent medium and comes back to the same medium. Total internal reflection (TIR) refers to the complete reflection of light within a transparent medium. Total internal reflection occurs in various electromagnetic, sound, and water waves. As a result, the light ray becomes trapped within the medium’s internal structure. The ray of light cannot leave and enter the other medium in this case instead, it is reflected into the first medium. Total internal reflection occurs when light entering at an interface between two different mediums is reflected within the medium without refraction, diffusion, transmission, scattering, or other related processes.

Angle of reflection formula