Question

The refractive index of diamond is much greater than that of ordinary glass. Is this fact of some use to a diamond-cutter? [3 MARKS]

Answer 1

Each point: 1 Mark

1. Refractive index of diamond is nearly 2.42. It is much larger than that of ordinary glass (nearly 1.5).
2. The critical angle for diamond is nearly 24⁰. This is much less than that of ordinary glass.
3. A skilled diamond cutter exploits the large range of angle of incidences (in the diamond) 24⁰ to 90⁰, to ensure that light entering the diamond gets totally internally reflected as many times as possible from many faces before getting out. This produces brilliance i.e., sparkling effect in the diamond.