Which device converts electrical energy into sound?

• A. Microphone
• B. Relay
• C. Earphones and Speakers
• D. Bells and Buzzers

Answer: (D)

When electrical energy is used to produce sound, you’re looking at an energy-to-sound transducer. Bells and buzzers fit this role because they convert electrical energy directly into mechanical motion that creates audible waves in the air. An electromagnet pulls or drives a diaphragm or a metal piece to strike a bell or vibrate rapidly, producing sound as long as current flows. This simple, direct conversion is what makes bells and buzzers classic examples of turning electricity into sound.

A microphone does the opposite: it turns sound into an electrical signal. A relay is just a switch controlled by electricity, not primarily a sound-maker. Earphones and speakers also convert electrical energy into sound, so they are valid sound producers too, but bells and buzzers are the straightforward, textbook examples of devices that generate sound from electrical energy.