Hook's law defines

Options

A. Stress
B. Strain
C. Modulus of elasticity
D. elastic limit

Answer

To solve the question regarding what Hook's Law defines, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Hooke's Law**: Hooke's Law states that the strain in a solid is proportional to the applied stress within the elastic limit of that material. Mathematically, it can be expressed as:
\[ \sigma = E \cdot \epsilon \]
where \( \sigma \) is the stress, \( E \) is the modulus of elasticity (Young's modulus), and \( \epsilon \) is the strain.

2. **Identify Key Terms**:
- **Stress**: The force applied per unit area within materials.
- **Strain**: The deformation experienced by the material in response to stress.
- **Modulus of Elasticity**: A measure of the stiffness of a material, defined as the ratio of stress to strain.
- **Elastic Limit**: The maximum extent to which a solid may be stretched without permanent alteration of size or shape.

3. **Analyze the Relationship**: According to Hooke's Law, the ratio of stress to strain is constant for a given material up to its elastic limit. This constant is known as Young's modulus.

4. **Conclusion**: Based on the definitions and relationships established by Hooke's Law, we conclude that Hooke's Law defines the modulus of elasticity, which is represented by Young's modulus.

### Final Answer:
Hooke's Law defines the **modulus of elasticity** (Young's modulus).

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