According to Hooke’s Law strain is proportional to the stress (under certain circumstances). In other words we can say that under certain conditions strain is directly proportional to the stress. This means that when more force is applied to pull the material the more it expands and when more compressed force is applied more it gets compact.
Mathematically ,
Strain α Stress
According to Hooke’s law,
Stress / Strain = E
Where E is a constant known as “Coefficient of elasticity” or “modulus of elasticity” or “Elastic Modulus”