The graph is a straight line passing through the origin. Mathematically,

Stress ∝ Strain ⇒ (stress/strain) = constant

**Modulus of Elasticity**

The constant is known as modulus of elasticity. Its unit is newton per meter squared. (Remember strain is a ratio and has no units, therefore, the units of modulus of elasticity and stress are same). Similarly, you can see from the above graph that the gradient of the graph (ΔF/Δl) also gives this constant.

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