Question

Hooke’s law defines,
A) Modulus of elasticity
B) Stress
C) Strain
D) Elastic limit

Answer 1

Hint: When force is applied to a material it deforms. However some materials regain their original dimensions after the load /force is removed. The elastic materials have this tendency.

Complete answer:
What is elasticity?
There are certain materials that on application of a load or force tend to get deformed. These materials after the load is removed regain the initial dimensions. This property of the material is called elasticity.
What is plasticity?
There are certain materials that on application of a load or force tend to get deformed. These materials do not regain their initial dimensions. In other words the materials tend to get permanently deformed on application of load. This property of the material is called plasticity.
Hooke’s law also known as law of elasticity expressed as $F_s=Kx$
Where,
$F_s=$ Force needed to expand or compress a spring (s)
$K=$ is constant factor characteristic of the spring (stiffness of spring)
$x=$ distance (which is to be compression or extended)
In Hooke’s law, the force is proportional to the extension or compression. Where, the distance $'x'$ is small compared to the total possible deformation of the spring.
So basically Hooke’s Law the ratio of stress to strain. This ratio is constant for a material and is known as the modulus of elasticity of the material.

Note: Hooke’s law holds in some situations where an elastic body is deformed, for example, musicians plucking a string of a guitar and such materials are known as Hooke an elastic or linear. The ratio of stress to strain is also called Young's Modulus and is different for different materials. It is also called the modulus of elasticity.