What is the use of knowing the charge on an electron?

Question

I want to know, what is the point of knowing the charge on an electron, what can we do with that value, what does it help us achieve???

Answer 1

It allows us to determine what electrons do when you apply forces to them. Since the force on an electron from an electric field is proportial to its charge, knowing its charge allows you to determine what electrons do. There are so many places where this is necessary I can even begin where to start.

The example you might be familiar with is a CRT tv, the old, non plasma or LCD tvs. Those work by shooting a beam of electrons and steering it across the screen with electric fields. an extremely simple calculation (assuming you know the charge to mass ratio of the electron) tells you what electric field you need to steer the beam. Electron charge enters all over the place in optics. It is necessary to find out how materials respond to electromagnetic waves. It is an important part of all vacuum electronics. Such as vacuum tubes, magnetrons, traveling wave tubes, etc.. Because you know the charge you can design these vacuum electronic devices which are used all over the place, especially in communication (that is how signals are sent from/to satellites). Most scattering problems require the electron charge, also many radiation problems (which use scattering) need to know the electron charge. In quantum problems it becomes important because it is the basic quanta of charge. When you get to very small scales things pop up that are integer multiples of the electron charge, such as current flowing in small devices. It comes up in virtually every plasma physics problem that isnt MHD.