A ray of light travels from a denser to a rarer medium. After refraction, it bends away from the normal. When we keep increasing the angle of incidence, the angle of refraction also increases till the refracted ray gazes along the interface of two media.The angle of incidence for which it happens is called critical angle.If the angle of incidence is increased further the ray wil not emerge and it will be reflected back in the denser medium. This phenomenon is called total internal reflection of light.
(i) A ray of light travels from a medium into water at an angle of incidence of 18° The refractive index of the medium is more than that of water and the critical angle for the interface between the two media is 20°. Which one of the following figures best represents the correct path of the ray of light?