text: As this quantity increases, a plot of its counterpart gives serrated bands in the Portevin-Le Chatelier effect.
full_question: As this quantity increases, a plot of its counterpart gives serrated bands in the Portevin-Le Chatelier effect. The gauge factor is the change in resistance, over resistance, divided by this quantity. Cold working results in the tangling of grain dislocations in this quantity's namesake "hardening". The time derivative of this quantity multiplied by viscosity equals the viscous force over area. The Poisson ratio is the negative ratio of it in the transverse and axial directions. The Cauchy, or engineering, definition of this quantity is the change in length over the original length. For 10 points, name this dimensionless quantity symbolized epsilon, which is often plotted against stress.
first_sentence: As this quantity increases, a plot of its counterpart gives serrated bands in the Portevin-Le Chatelier effect.
raw_answer: engineering strain [or strain rate] 