Modulus of Elasticity (Elastic Modulus) is a physical quantity that measures how much a material resists deformation (stretching or compressing) when a force is applied.

Definition

Modulus of elasticity is the ratio of stress to strain within the elastic limit of a material.

E = Stress/Strain

• Stress = Force applied per unit area

• Strain = Change in length divided by original length

Simple Meaning

It tells us how stiff or flexible a material is.

• A large modulus of elasticity → material is very stiff (like steel).

• A small modulus of elasticity → material is more flexible (like rubber).

Unit

The SI unit of modulus of elasticity is Pascal (Pa) or N/m².

Types of Modulus of Elasticity

1. Young’s Modulus – For stretching or compressing a material.

2. Bulk Modulus – For change in volume when pressure is applied.

3. Shear Modulus (Rigidity Modulus) – For change in shape when a tangential force is applied.

Example

• Steel has a very high modulus of elasticity, so it does not stretch easily.

• Rubber has a low modulus of elasticity, so it stretches easily.

 In short: Modulus of elasticity measures the stiffness of a material and its ability to return to its original shape after the force is removed.