The ratio of stress to strain in a material within the elastic limit is called?

• A. Both A and B
• B. Young's modulus
• C. The modulus of elasticity
• D. The index of refraction

Answer: (B)

This question is about how stiff a material is in its elastic range. When a material is stressed within its elastic limit, stress and strain are proportional, and the constant of proportionality is the modulus of elasticity. The standard term used for this ratio in uniaxial loading is Young's modulus. It directly measures stiffness: higher values mean the material deforms less under a given load. The modulus of elasticity is essentially the same property, just another common name, which is why Young's modulus is the best and most specific answer. The index of refraction concerns light, not mechanical deformation, so it’s not correct here.