Electret

An electret is a special kind of material that has a charge (like when you rub a balloon on your hair and it sticks to the wall). This charge stays on the material for a very long time, even if it's not connected to anything else. Think of it like a battery that never runs out.

This special material is used in lots of things we use every day, like microphones and speakers. When you talk into a microphone, the electret material inside picks up the sound and turns it into an electrical signal that can be sent to a speaker which changes it back into sound.

The electret material is really important because it helps make sure the signal is clear and strong, and it doesn't need any extra power to work. It's like having a super power that never goes away!