Modulus of Rigidity (Shear Modulus)

The modulus of rigidity is a physical quantity that measures the ability of a material to resist deformation when a shear force is applied.

In simple words, it tells us how difficult it is to change the shape of a material without changing its volume.

Definition:
The modulus of rigidity is defined as the ratio of shear stress to shear strain within the elastic limit of a material.

G = Shear Stress/Shear Strain

Where:

• G = Modulus of rigidity

• Shear Stress = Force applied per unit area parallel to the surface

• Shear Strain = The angular deformation produced in the material

SI Unit:
The SI unit of modulus of rigidity is Pascal (Pa) or N/m².

Example:
Materials like steel and iron have a high modulus of rigidity, which means they resist shape change strongly, while rubber has a low modulus of rigidity and deforms easily.

Conclusion:
The modulus of rigidity helps us understand how a material behaves when twisting or shear forces act on it and is important in engineering and structural design.