 # What is the relation between compressibility and Bulk modulus?

We know that the physics concepts compressibility and bulk modulus are interconnected. These two concepts mainly deals with pressure and volume. Before learning on the relation between compressibility and Bulk modulus let us know exactly what is meant by these words.

## What is compressibility?

Compressibility can be defined as the property of being reduced to a smaller space by pressure. The compressibility of fluid is basically a measure of the change in density that will be produced in the fluid by a specified change in pressure. Gases are, in general, highly compressible whereas most liquids have very low compressibility.

## What is bulk modulus?

Bulk modulus of a substance is defined as the ratio of infinitesimal pressure increase to a decrease of the volume. Bulk modulus is meaningful only for a fluid. It is denoted as either K or B.

## Relationship between compressibility and bulk modulus

The relation between compressibility and bulk modulus is that the inverse of compressibility is known as the bulk modulus.

• Bulk modulus is defined as the ratio between increased pressure and decreased volume of the material. It is denoted by the letter K.
• Compressibility is defined as the ratio of change in volume to the change in pressure. It is denoted by the letter B. For fluids, compressibility depends on either the adiabatic or isothermal process.