Poisson’s ratio

Poisson’s ratio: σ

When a tensile stress is applied to a wire, the wire undergoes not only an extension of length in the direction of the force but also a contraction in its thickness. The ratio of decrease in thickness to the original thickness in lateral direction is known as lateral contraction.

The ratio of lateral contraction to linear elongation is called Poisson’s ratio.

Poisson ‘ s ratio σ = Lateral contraction/ Linear elongation

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