## Elastic Moduli – Class 11 | Chapter – 9 | Physics Short Notes Series PDF for NEET & JEE

Elastic Moduli: Elastic moduli are material properties that describe a material’s stiffness or resistance to deformation under applied stress. Elastic moduli are important material properties that are used in a variety of engineering applications. For example, they are used to calculate the deformation and stress in structures and components, to design materials with specific properties, and to understand the behavior of materials under different types of loads or stresses.

## Types of Elastic Moduli

There are three main types of elastic moduli:

• Young’s modulus (E): Young’s modulus is a measure of a material’s stiffness in the elastic region of the stress-strain curve. It is defined as the ratio of the stress applied to a material to the resulting strain in the linear elastic region. Young’s modulus is typically used to describe the elasticity of materials like metals, ceramics, and composites.
• Shear modulus (G): Shear modulus is a measure of a material’s resistance to shear deformation, which is deformation that occurs when two layers of material slide past each other. Shear modulus is defined as the ratio of shear stress to shear strain in the elastic region. Shear modulus is typically used to describe the elasticity of materials like metals, polymers, and rocks.
• Bulk modulus (K): Bulk modulus is a measure of a material’s resistance to volumetric deformation under uniform stress. It is defined as the ratio of volumetric stress to volumetric strain in the elastic region. Bulk modulus is typically used to describe the elasticity of fluids, gases, and some solids like rubber and foam.

## Elastic Moduli of Materials

The following table lists Young’s modulus, shear modulus and bulk modulus for common materials.

 Material Young’s modulus (E) in GPa Shear modulus (G) in GPa Bulk modulus (K) in GPa Glass 55 23 37 Steel 200 84 160 Iron 91 70 100 Lead 16 5.6 7.7 Aluminium 70 24 70

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