Final answer:
An electric bell works by sending electricity through wires to move a piece of metal back and forth, creating a ringing sound, similar to how hitting a drum creates a noise.
Step-by-step explanation:
To explain an electric bell to a 3-year-old, you could compare it to something familiar, like a drum. An electric bell has parts inside that work together to make a ringing noise, just like how hitting a drum makes a sound. When someone pushes a button, electricity goes through wires (like water through pipes) to the bell. Inside the bell, the electricity makes a piece of metal move back and forth really fast, hitting another piece of metal, which makes the ringing sound you hear, just like when you hit a drum with a drumstick.