The correct answer is Total internal reflection. Explanation & Key Takeaways: • Total internal reflection • It is the complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. • The phenomenon occurs if the angle of incidence is greater than a certain limiting angle, called the critical angle. • Examples - • The formation of a mirage. • Shining of an empty test tube in water. • Shining of a crack in a glass vessel. • Sparkling of a diamond. • Transmission of light rays in an optical fibre. Related Concepts: • Dispersion • Dispersion is defined as the spreading of white light into its full spectrum of wavelengths. • Examples - • Rainbow formation, • Petrol poured on the water will show different colours, • The prism splits the light into different colours on passing through it, • Dispersion of colours in soap bubbles, etc. • Diffraction • Diffraction is the spreading of waves around obstacles. • Examples - • X-Ray Diffraction, • Water passing from a small gap, • Solar or lunar corona, sound, etc. • Reflection • Reflection occurs when a light ray hits a surface and bounces off and returns to the medium from which it originated. • Examples - • Reflection of light in the mirror, in a water pool, glowing stars, lighting of the moon at night, etc.