A ray of light travelling in a liquid is incident at an angle of 58°at the liquid-glass interface. At A, the ray of light suffers total internal reflection and at B, it grazes the glass-air interface as shown in the figure .
If the refractive index of the material of the glass is 1.5, find the:
i. Critical angle for the glass
ii.Refractive index of the liquid
Answers
Answer:When a ray of light AO passes from an optically denser medium to a rarer medium, at the interface XY, it is partly reflected back into the same medium along OB and partly refracted into the rarer medium along OC as shown in figure.
If the angle of incidence is gradually increased, the angle of refraction r will also gradually increase and at a certain stage r becomes 90o. Now the refracted ray OC is bent so much away from the normal and it grazes the surface of separation of two media. The angle of incidence in the denser medium at which the refracted ray just grazes the surface of separation is called the critical angle c of the denser medium.
If i is increased further, refraction is not possible and the incident ray is totally reflected into the same medium itself. This is called total internal reflection.