The ratio of stress to strain in the elastic region is also called which other term?

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

Answer: (B)

In the elastic region, stress and strain are proportional, and the constant of proportionality is a measure of how stiff the material is. This constant is known as Young's modulus. It’s the ratio of stress to strain under uniaxial loading, so it directly quantifies how much a material resists deformation. Some people use the term modulus of elasticity to refer to the same property, but in this context the standard term for the ratio itself is Young's modulus. The index of refraction is an optical property and has no relation to the mechanical stress–strain response, so it’s not involved here.