How did Millikan's oil drop experiment lead to quantum nature of electric charge?

Millikan's oil drop experiment proved that electric charge is quantized.

At the time, there was still great debate whether electric charge was continuous or not.

Millikan believed that there was a smallest unit of charge, and he set out to prove it.

This was the big result of the oil drop experiment.

That he could also determine the charge of the electron was a secondary benefit.

This was probably one of the most significant experiments ever carried out.

Explanation:

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards