Kā skaļruņi pārvērš elektrību skaņā
When things shake or vibrate, they make sounds that we can hear in the world around us. Sound is invisible most of the time, but sometimes you can actually see it! If you hit the kettle drum with a stick, you'll see the taut drum head go up and down very quickly after a while - pumping the sound waves into the air. Speakers work in a similar way.
On the front of the speaker, there is a fabric, plastic, paper, or lightweight metal cone (sometimes called a diaphragm), not the same as the drum head (grey in the image below). The outside of the cone is fixed to the outside of the speaker's rounded metal rim. The inner part is attached to an iron coil (sometimes called a voice coil, pictured in orange) in a hollow ring in front of a permanent magnet (sometimes called a field magnet and yellow). When you connect speakers to the stereo, the electrical signal goes through the speaker cable (red) into the coil. This turns the coil into a makeshift magnet or electromagnet. As current flows back and forth in the cable, the electromagnet attracts or repels the permanent magnet. This moves the coil back and forth, pulling and pushing the speaker cone. Like a drum head vibrating back and forth, a moving cone pump transmits the sound into the air. That's why speakers are technically called drivers: they "drive" (move) air to produce sound.
