The modulus of rigidity, also known as the shear modulus, represents a material's resistance to shear deformation. It is defined as the ratio of shear stress to shear strain within the elastic limit of the material.

Shear Stress (τ): Force applied parallel to the surface per unit area

Shear Strain (γ): Angular distortion produced

The formula is:

G = τ / γ


Materials with a higher shear modulus are more resistant to shape change under shear forces.