Question

what is the difference between optical density and mass density ....plz guys help me.........​

Answer 1

Optical density should not be confused with mass density, which is mass per unit volume. It is possible that mass density of an optically denser medium may be less than that of an optically rarer medium (optical density is the ratio of the speed of light in two media).

For example, turpentine and water. Mass density of turpentine is less than that of water but its optical density is higher.

Answer 2

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optical density is the measure of absorbance, and is defined as the ratio of the intensity of light falling upon a material and the intensity transmitted, on the other hand mass density tells us that how much amount of mass is contained per unit volume.