We have just begun exploring the vast world of electricity, magnetism and their coupled effects of electromagnetism with the middle-schoolers. Almost everything that we can think of around and within us is related to these effects; whether it is the awe-inspiring lightning strikes on a stormy day or all the electrical/ electronic gadets and machines that rule our world today. Can we even imagine a world without electricity and magnetism? And I am not talking of man-made electricity here; our very existance is based on the electrical impulses that control every movement of muscles in our bodies.

It is in this context that I find this question really interesting because it is not often that we associate sound with electricity. This question has an uncanny resemblance to the “how stuff works” questions but the ingenuity lies not in the question itself but the context in which it was raised. This is what hands-on STEM learning does – it creates a strong  network of fundamental core concepts and a motivation to learn. 

Coming back to the question itself, in the simplest of terms, a microphone essentially converts the sound (pressure) waves into a  varying electrical current that can be modified as required. The sound waves are essentially mechanical pressure waves. So, when we speak in front of a microphone, the pressure waves are detected by a small diaphragm (thin sheet) inside it. This movement of the diaphragm is then converted into a electrical signal. There are more than one ways of doing so such as by moving a coil within/near a magnet or moving one of the plates of a capacitor.

Details about the kinds of microphones can be found here. I would not want to go into the details because this post is not about providing textbook answers. Rather these posts exemplify how the thought process of children evolve as they understand concepts by doing and asking as opposed to simply reading or listening.