How does a phone let us talk?

You hold a phone to your ear, say “Hello!” and a friend far away hears you straight away. How does your voice travel so fast?

Your voice becomes a code

When you talk, the air wobbles in little waves. The tiny microphone inside the phone feels those wobbles and turns them into a code — a long string of fast signals, almost like dots and dashes.

This code is small and quick. It can travel much faster than your voice could ever shout across a room.

The code zooms away

From a mobile phone, the code flies out as invisible radio waves. They jump to a tall tower nearby, then race through wires and cables — sometimes even under the sea — all the way to your friend’s phone.

All of this happens in less than a second, so it feels like you are talking right next to each other.

Code turns back into sound

Your friend’s phone catches the code and does the trick in reverse. A little speaker wobbles the air again, copying the exact sound of your voice. Now your friend hears “Hello!” — and can answer you back the same way.

Wonder fact: Signals in cables can travel close to the speed of light — fast enough to zip around the whole Earth several times in one second!