Right, so the Young's modulus of a material is a measure of it's rigidity. The higher the value of the Young's modulus, the more rigid the material is.

Ok, so the Young's modulus, E, is equal to the stress that the material experiences divided by the strain experienced by the material.

The stress, σ, of a material is equal to the force, F, applied to this material, divided by the area, A, upon which this force is applied. The equation for this is:

σ = F/A

On the other hand, the strain, ε, of the material is equal to the extension of the material, e (how much the material has extended by having this force applied to it), divided by the original length, l, of the material. The equation for strain is

ε = e/l

The Young's modulus is equal to the stress divided by the strain, so:

E= σ/ε = (F/A)/(e/l) = (F*L)/(A*e)

So, E = (F*l)/(A*e)

For example, If a metal wire of original length 2cm