Question

What affects Young’s modulus?

Answer 1

Stress is the force per unit area while strain is the ratio of change in dimensions to the initial dimensions. Young’s modulus is the stress applied per unit strain in the body, it is the measure of stiffness of a material. Young’s modulus is also known as the modulus of elasticity and it is a constant quantity as it is a property of the material.

Complete answer:
When a body is stretched, it experiences a force per unit area of the body, this force is known as stress. It is denoted by $\sigma$ and it is given as-
$\sigma =\dfrac{F}{A}$
Here, $F$ is the force applied
$A$ is the area of cross section
Strain is the relative change in the dimensions of a body when stress is applied. It is a unitless quantity. There are different types of strain; longitudinal strain is the ratio of change in length to the initial length, shearing strain is the ratio of displacement of a surface to its height while the bulk strain is the change in volume of the body to its initial volume.
The young’s modulus, also known as the modulus of elasticity, is the measure of stiffness of a body. It is the stress applied to the body per unit strain produced in the body. Therefore,
$Y=\dfrac{\sigma }{\varepsilon }$
Here, $Y$ is the Young’s modulus
$\varepsilon$ is the strain produced in the body
Young’s modulus is the property of a body therefore, it is different for different materials, its value depends on the temperature and pressure.
Therefore, external temperature and pressure affects the value of Young’s modulus.

Note:
Strain is unitless because it is the ratio of similar quantities. When a body is under the action of a stress, a restoring force is developed inside it due to which it comes back to its original shape after being stretched. Young’s modulus is the constant of proportionality in the relation between stress and strain as described by Hooke’s law.