A tension of 20 ~N is applied to a copper wire of cross sectional area 0.01 ~cm ^2 , Young's modulus of copper is 1.1 10¹¹ ~N / m ^2 and Poisson's ratio is 0.32 . The decrease in cross sectional area of the wire is

Step-by-step solution

Given, =0.32, F=20 ~N A=0.01 ~cm ^2=0.01 10⁻³ ~m and Y=1-1 10¹¹ ~N / m ^2 We know that l l = F A Y = 20 0.01 10⁻³ 1.1 10¹¹ =18.1 10⁻⁷ and we also known gathered = - r / r / / - r r =0.32 18.1 10⁻⁷=5.79 10⁻⁷ gathered Hence, decrease in cross reactional area of wire is aligned A=2 r r A & =2 5.79 10⁻⁷ 0.01 10⁻³ & =0.158 10⁻¹⁰ ~m ^2 & =1.26 10⁻⁶ ~cm ^2 aligned