Energy transformation demonstration

Earlier this year, a friend of mine was organizing an event to promote eco-friendly behaviors. She wanted someone to talk about our relationship with energy and asked me to give a presentation on the topic, which I agreed to. I wanted the presentation to be entertaining so I designed a set of hardware demonstrations aimed at explaining physical concepts related to energy.

The core idea was to show how energy is not created but transformed from one form to another. Consequently, if one wants to use electricity to power a light bulb, this electricity must be transform from mechanical or chemical energy, for example. Additionally, the light bulb transforms electrical energy into light, but also heat, which is an undesirable byproduct of the transformation. This brings the concept of efficiency, which is to be maximized as much as possible so as to reduce energy "waste".

To show the transfer of electrical energy, I designed a simple IoT wattmeter using an ESP32 and current sensor. The IoT nature of the meter allowed participants to view the power flowing through the device in real time from their smartphones.

In order to "feel" the challenges of transforming energy of some sort into electricity, I took a brushed DC motor and attached simple crank handle to it, thus turning it into an electrical generator. However, the crank can be turned in both directions and the output voltage varies greatly depending on the rotation speed, I designed a simple rectifying and stabilizing circuit using diodes and a buck converter.

As such, the participants would crank the motor as hard as possible in order to light a bulb or power another motor while witnessing their power output on a web interface.