Book 3, Question 85
Why Do Speakers Make Sound?
A speaker has a paper or plastic cone that pushes air. And pushing air in a pattern is exactly what sound is! Inside, electricity runs through a coil beside a magnet.
From the book
Page from A Million Whys Book 3
More fun facts
- A speaker sends changing electric current through a coil of wire that sits near a magnet.
- The current makes the coil move back and forth very quickly.
- The moving coil pushes on the air, and that makes sound waves.
- The changing electric signal from a song makes a changing magnetic field that matches the original sound.
- You can build a simple working speaker at home from household materials.
- Some slim speakers use a magnetic liquid called ferrofluid to make sound louder and clearer, a technology featured in NASA's Spinoff report.
Sources: Scientific American, BBC, NASA
Questions kids ask
What is inside a speaker?
A coil of wire and a magnet. Electric signals make the coil move back and forth, which pushes the air to make sound.