Modulus of Elasticity:
The modulus of elasticity is a measure of a material's ability to deform elastically under stress. It quantifies the relationship between stress (force per unit area) and strain (deformation) in a material. It is commonly referred to as Young's modulus and is denoted by the symbol E.

Steel vs Concrete:
Steel and concrete are two widely used construction materials with different properties. The modulus of elasticity of a material indicates its stiffness or ability to resist deformation under stress. In the case of steel and concrete, the modulus of elasticity differs significantly.

Explanation:
1. Steel:
Steel is known for its high strength and rigidity. It has a high modulus of elasticity, which means that it is more elastic compared to concrete. When steel is subjected to stress, it undergoes minimal deformation and can return to its original shape once the stress is removed. This property makes steel suitable for applications where strength and stability are essential, such as structural beams and columns in buildings, bridges, and other infrastructure.

2. Concrete:
Concrete, on the other hand, has a lower modulus of elasticity compared to steel. It is a composite material made of cement, aggregates (sand and gravel), and water. While concrete is strong in compression, it is relatively weak in tension. When subjected to stress, concrete undergoes more deformation or strain compared to steel. It is less elastic and exhibits more plastic behavior. Plastic behavior refers to the ability of a material to undergo permanent deformation without fracturing.

3. Significance:
The difference in modulus of elasticity between steel and concrete is significant in structural design. When designing structures, engineers need to consider the compatibility of materials used. Steel and concrete are often used together in composite structures like reinforced concrete. The high modulus of elasticity of steel helps to resist tensile forces, while the lower modulus of elasticity of concrete helps to provide stability and confinement to the steel reinforcement.

Conclusion:
In conclusion, the modulus of elasticity of steel is higher than that of concrete, indicating that steel is more elastic compared to concrete. This higher elasticity allows steel to undergo less deformation under stress, making it suitable for load-bearing applications where strength and rigidity are essential. On the other hand, concrete exhibits more plastic behavior due to its lower modulus of elasticity, making it suitable for applications where deformation without fracture is desired.