Thus, with the increase in height, the optical density also increases and vice versa. Hot air has a small refractive index and is less dense.Īlternatively, the cold air has a large refractive index and is denser. According to this phenomenon, the air that is present near the ground gets hotter as compared to the other place above it. You can observe this optical phenomenon during the hot summer days when total internal reflection occurs. Mirage is an optical illusion concept that is based on total internal reflection. The cut of the diamond is made in such a way that the light that once entered the diamond remains in it and comes out from the top after suffering multiple reflections. Because of the lower diamond and air interface, the beam of lights entering into the diamond remains inside the diamond and suffers multiple internal reflections. The reason is due to the lower diamond and air interface. The shine of the diamond is due to the phenomenon of total internal reflection. Now that you’ve got an idea of what total internal reflection is, it’s time to discuss the most important applications of total internal reflection.ĭiamond is popular because of its amazing shine and its glamorous look. Total internal reflection and its applications. If the incident beam of light satisfies the two conditions, it will lead to total internal reflection. The critical angle should always be less than the angle of incidence (made by the incident ray).The beam of incident light should travel from a more dense medium to a less dense medium.Important Conditions For Total Internal Reflectionįor total internal reflection to take place, the light must satisfy the below-mentioned two conditions. Here is the formula of critical angle in the sine form:- sin Ө = n 2 / n 1Ĭritical angle in the formula is defined as:- the sine of critical angle is equal to the ratio of the refractive index of the second medium to the refractive index of the first medium. N 2 is the refractive index of the second medium. N 1is the refractive index of the first medium and Total internal reflection =n 1 / n 2 = sin(i) / sin(r). In other terms, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is known as total internal reflection. Total internal reflection is the ratio of the refractive index of medium 1 to the refractive index of medium 2. And, this phenomenon is known as total internal reflection. In such a case, the light ray that is made to strike the surface reflects back into the same medium. The third case is when the critical angle is less than the angle of incidence.

In such a case, the angle of refraction is always 90°. This specific angle of incidence is termed as the critical angle, denoted by ic.

At a certain angle of incidence, the incident light ray passes straight along the water surface.

During the refraction, the light ray bends away from the normal, increasing the angle of refraction.

When the light travels from water (high refractive index) to air (low refractive index), the light ray gets refracted at the junction point.

Let’s take an example to discuss total internal reflection in detail.Ĭonsider water and air as the two mediums in which the refraction of light takes place. This, in turn, makes the angle of refraction more than the angle of incidence. When the travel medium changes, the ray gets bent away from the normal. In short terms, total internal reflection is defined as the light ray that travels from an optically denser medium to an optically rarer medium. Read further to find more about total internal reflection and its applications. When a light incident on a refracted surface at an angle and refracted at 90 angle then incident angle is defined as critical angle.

When the angle of incidence made by the incident ray is greater than the critical angle, the phenomenon is known as total internal reflection. In such a phenomenon, some portion of the light gets reflected back into the same medium and another portion of the incident light gets refracted into the different medium. When a light beam or ray travels from an optically denser medium to a rarer medium or less optically denser medium, internal reflection occurs. Internal reflection is a part of optics that explains the concept of travelling of light.

Internal reflection definition