The stress at which any material transforms from elastic to plastic material is known as-

Question

Question

Answer 1

CONCEPT:

Stress: Stress is the ratio of the load or force to the cross-sectional area of the material to which the load is applied. It is denoted by σ.
- The standard unit of stress is N/m².
The maximum stress that a material can bear before fracture is called Ultimate stress.
Strain: Strain is a measure of the deformation of the material as a result of the force applied. The strain is a unit less quantity. It is denoted by ϵ.
Hooke's Law: The force needed to extend or compress a spring by some distance is proportional to that distance.
Stress-strain curve: Stress-strain curve is a graphical representation of the behavior of a material when it's subjected to a load or force. The two characteristics that are plotted are stress on the y-axis and strain on the x-axis.

EXPLANATION:

The stress at which any material transform from elastic to plastic behaviour is called the yield strength. So option 2 is correct.
The Yield strength of a material is a constant that represents the maximum limit of elastic behaviour of that material.