Correct Option (a):
Total Internal Reflection (TIR) occurs when two primary conditions are met:
- Light must travel from an optically denser medium to an optically rarer medium.
- The angle of incidence in the denser medium must be greater than the critical angle for the interface between the two media.
Diamond has a refractive index of approximately 2.42, which is significantly higher than that of glass (approximately 1.5 to 1.6). Therefore, when light travels from diamond to glass, it moves from an optically denser medium to an optically rarer medium. This satisfies the first condition for TIR, making it possible for total internal reflection to occur if the angle of incidence exceeds the critical angle.
Incorrect Options:
Option (b) Water to glass: Water (refractive index ~1.33) is optically rarer than glass (refractive index ~1.5-1.6). For total internal reflection to occur, light must travel from a denser to a rarer medium. Hence, TIR is not possible in this scenario.
Option (c) Air to water: Air (refractive index ~1.00) is optically rarer than water (refractive index ~1.33). As light travels from a rarer to a denser medium, total internal reflection cannot occur.
Option (d) Air to glass: Air (refractive index ~1.00) is optically rarer than glass (refractive index ~1.5-1.6). Since light travels from a rarer to a denser medium, total internal reflection is not possible.