Answer:
When a buzzer is associated with some kind of circuit and one press the key then the completion of the circuit takes place. As a consequence, the current will begin to flow from the cell or the battery and moves towards the buzzer. Therefore, the sound is generated by the buzzer because of the flow of the electrical charge through it.
After going through the buzzer, the electric charges again moves towards the battery. Thus, the electric charges move in the complete circuit.
