Correct Answer - Option 1 : 0.4

**Concept:**

**E = 2G(1 + v)**

where E = Modulus of elasticity, G = Modulus of rigidity, ν = Poisons ratio.

**Calculation:**

**Given:**

Poisson's ratio, v = 0.25

the ratio of modulus of rigidity to modulus of elasticity = \(\frac{G}{E}\)

\(\frac{G}{E} = \frac{1}{{2\left( {1 + v} \right)}}\)

\(\frac{G}{E} = \frac{1}{{2\left( {1 + 0.25} \right)}}\)

\(\frac{G}{E} = 0.4\)

**Hence the required value of the ratio of modulus of rigidity to modulus of elasticity is 0.4.**