question_answer

Graphite consists of planes of carbon atoms. Between atoms in the planes there are only weak forces. What kind of elastic properties do you expect from graphite?

Answer:

                Due to weak attractive forces between carbon atoms of different planes, it is easier to produce a large shearing strain by moving one plane of atoms over the other with the application of a small tangential stress. Now \[\text{Modulus of rigidity,}\eta \text{=}\frac{\text{Tangential stress}}{\text{Shear strain}}\] Hence graphite should possess a small modulus of rigidity.