Total Internal Reflection and Critical Angle
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This document discusses total internal reflection and the critical angle. It defines refractive index as the ratio of light speed in a vacuum to light speed in a medium. When light passes from one medium to another of different density, refraction occurs. As the angle of incidence increases, so does the angle of refraction, until reaching the critical angle. At the critical angle, the light ray follows the surface instead of entering the second medium. Above the critical angle, total internal reflection occurs and the light is reflected back into the first medium. Total internal reflection and critical angles depend on the refractive indices of the materials, and have applications in fiber optics, prisms, periscopes, and more.
Total Internal Reflection and Critical Angle
- 1. TOTAL INTERNAL REFLECTION AND CRITICALANGLE Presented By:- Amit Raikar
- 2. What is Refractive Index? The refractive index of a medium is defined as the ratio of the velocity of light in a vacuum to the velocity of light in the medium. A ray of light travels more slowly in an optically dense medium than in one that is less dense.
- 3. What is Refraction? When a ray is incident on the interface between two dielectrics of differing refractive indices (e.g. glass–air), refraction occurs
- 4. As the angle of incidence Increases, the angle of refraction Increases.
- 5. What is Critical Angle? •At a certain angle, the refracted ray follows a path exactly along the surface of the dense medium. •When the angle of refraction is at 90° the incident angle is called the “Critical Angle”
- 6. What is Total Internal Reflection (TIR)? •If the incident ray is increased beyond the critical angle, the light is no longer refracted • Instead, it is reflected back inside the medium •This is called “total internal reflection”
- 7. Total Internal Reflection A light ray hits the inside face of a semicircular block.
- 9. Conditions for TIR & Critical Angle Light is travelling slower in the first medium than in the second medium (v1 < v2) Thus light is moving from medium of higher refractive index to one of lower refractive index (n1 > n2) Critical angle (C) is defined when the angle of refraction is 90° to the normal (θ2 = 90°) TIR occurs when angle of incidence is larger than the critical angle (θ1 > C)
- 11. Critical angles of different materials Medium Refractive Index Critical Angle Glass 1.50–1.70 30°–42° Water 1.33 49° Perspex 1.5 42° Diamond 2.42 24°
- 12. Applications of TIR TIR in Fiber Optics Communication Endoscopes TIR in Prism Periscopes Binoculars Single Lens Camera Retro Reflectors
- 13. Communication
- 14. Endoscopes
- 15. Periscopes
- 16. Binoculars
- 18. Recto Reflectors
- 19. Thank You!