7. Relative density

The density of a particular substance, under specific conditions, remains the same. Therefore, the density of a substance is one of its characteristic properties. It is different for different substances.
For example, the density of gold is 19300 $\mathit{kg}/m^3$, while that of water is \(1000\) $\mathit{kg}/m^3$. The density of a given sample of a material can help us to determine its purity. It is easy to express the density of a substance in comparison with that of water.

 

 

The relative density has similar quantities in numerator and denominator. Therefore, it has no unit.

 

Example:

1. The density of water is ${10}^3$ $\mathit{kg}/m^3$. Find the density of silver, whose relative density is \(10.8\).

 

Given data:

Relative density of gold \(=\) \(10.8\)

Density of water \(=\) ${10}^3$ $\mathit{kg}/m^3$

  

To find: Density of the material

 

We know,

 

 

Apply the known values,