1-you know when a circuit is complete / closed the buzzer will go on or the bulb glows. But when the circuit is incomplete/ open then the buzzer will be on or the bulb won't glow
2-That electric potential energy changes to regular electric energy as the electrons move around the circuit. Then, that electric energy is transferred to the components in the circuit. If the circuit contains a bulb, it comes out as light energy and wasted heat energy
