Question

For a given material, the Youngs modulus is $2.4$ times that of (rigidity modulus, then Poissons ratio is

• A. 0.2
• B. 0.4
• C. 4.2
• D. 2.4

Answer 1

Answer: (A)

0.2

Answer 2

The fractional change in the transverse length is proportional to the fractional change in the longitudinal length. The constant of proportionality is called Poisson's ratio. In terms of Youngs' modulus and rigidity modulus, it is given by $\sigma=-\frac{\Delta d / d}{\Delta L / L}$ $=\frac{Y}{2 \eta}-1$ $Y=2.4 \eta$ $\therefore \sigma=\frac{2.4 \eta}{2 \eta}-1=0.2$