What are examples of electric force?

Well, there are essentially two forces in an atom. They are the strong force (which holds a nucleus together) and the electric force, which holds electrons in an atom.

In short, this works because positive and negative charges attract each other. Because the nucleus (protons and neutrons) is positive, and the electrons surrounding it are negative, they are attracted. The result is that the electrons don't fly off in all directions!

Because this force describes one specific phenomenon, I can't really give an example. However, if the question meant "what's an example of electrons having an impact in atoms", then I would go with lightning. This happens when negatively charged atoms (electrons!) build up at the bottom of a cloud, and gain enough energy to 'fly' across the ionized air to the ground, which is positively charged due to the repulsion of electrons