How does Young's modulus change with rise in temperature?

Options

A. 1) increases
B. 2) decreases
C. 3) remains unchanged
D. 4) None of these

Explanation

To understand how Young's modulus changes with a rise in temperature, we can break down the explanation into the following steps:

### Step-by-Step Solution

1. **Definition of Young's Modulus**:
Young's modulus (E) is defined as the ratio of tensile stress (force per unit area) to tensile strain (proportional deformation in length) in a material. It is a measure of the stiffness or rigidity of a material.

2. **Effect of Temperature on Materials**:
When the temperature of a material increases, the kinetic energy of its molecules also increases. This leads to increased molecular vibrations and can cause the material to become softer.

3. **Softening of Materials**:
As the temperature rises, many materials (especially metals and polymers) tend to lose their rigidity and become more ductile or malleable. This softening effect means that the material can deform more easily under stress.

4. **Loss of Elasticity**:
With the increase in temperature, materials generally lose some of their elastic properties. Elasticity refers to the ability of a material to return to its original shape after the stress is removed. As elasticity decreases, the material cannot withstand the same amount of stress without deforming permanently.

5. **Conclusion on Young's Modulus**:
Since Young's modulus is a measure of rigidity, and rigidity decreases as the material becomes softer and less elastic with an increase in temperature, it follows that Young's modulus will also decrease with rising temperature.

6. **Final Statement**:
Therefore, we can conclude that Young's modulus decreases with an increase in temperature.

### Summary
In summary, as the temperature of a material rises, its Young's modulus decreases due to the softening of the material and loss of elasticity.