Here are some common examples:

* Batteries: Chemical reactions inside a battery create a potential difference between its terminals, pushing electrons from the negative terminal to the positive terminal.

* Generators: Generators use electromagnetic induction to generate a potential difference by rotating a coil of wire within a magnetic field.

* Solar cells: Solar cells convert light energy into electrical energy, creating a potential difference.

* Power outlets: Power outlets provide a potential difference, typically 120V or 240V, that is supplied by a power plant.

In summary: A potential difference is essential for electrons to flow in a circuit, and it is created by a source of electrical energy.