Find out, from Table 10.3, the medium having highest optical density.Also, find the medium with lowest optical density.
As we know optical density is the tendency to hold(absorb) the light. So
more refractive index = more absorbing power = more optical density.
It can be observed from table 10.3 that diamond and air respectively have the highest and lowest refractive index. Therefore, diamond has the highest optical density and air has the lowest optical density.