Modulus of elasticity is a quantity that measures an object or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it.

## There are basically three types of modulus of elasticity:

### 1. Young's Modulus-

Young's modulus, or the Young modulus, is a mechanical property that measures the stiffness of a solid material. It defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material in the linear elasticity regime of a uniaxial deformation. At near-zero stress and strain, the stress–strain curve is linear, and the relationship between stress and strain is described by Hooke's law that states stress is proportional to strain. The coefficient of proportionality is Young's modulus. The higher the modulus, the more stress is needed to create the same amount of strain; an idealized rigid body would have an infinite Young's modulus

### 2. Shear Modulus-

Shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is defined as the ratio of shear stress to the shear strain. The shear modulus is concerned with the deformation of a solid when it experiences a force parallel to one of its surfaces while its opposite face experiences an opposing force (such as friction). In the case of an object shaped like a rectangular prism, it will deform into a parallelepiped.

### 3. Bulk Modulus-

The bulk modulus (K or B) of a substance is a measure of how resistant to compression that substance is. It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume. Bulk modulus of elasticity is one of the measures of mechanical properties of solids, the more the value of K for a material, higher is its nature to be incompressible. For example, the value of K for steel is 1.6×1011N/m2 and the value of K for glass is 4×1010N/m2. Here, K for steel is more than three times the value of K for glass.

**SELF TYPED***SOURCE: Internet and Books*