Modulus of Rigidity (C, N or G)

With in elastic limit the ratio of shear stress(q) to the shear strain(Φ) is constant and this constant is called as "Modulus of Rigidity".
It is denoted by "C" (capital letter C), "N" (capital letter N) or "G" (capital letter G).It is also known as shear modulus.
Mathematically,