The poisson ratio of a material is 0.5 if a force is applied to a wire of this material, there is a decrease in the cross sectional area by 4% what is the percentage increases in the length.

Explanation

`A = pir^(2)`, so `(Delta A)/(A) = 2(Delta r)/(r ) = (4)/(100)`
given `sigma = (Delta r//r )/(Deltal//l) = (1)/(2)` or `(Delta l)/(l) = (2 Delta r)/(r ) = (4)/(100)`
`:.` % increase in length
`(Delta l)/(l) xx 100 = (4)/(100) xx 100 = 4%`