This tutorial instructs you how to use the LDR light sensor with Arduino UNO R4. The light sensor used in this tutorial is a photoresistor, which is also called light-dependent. Build a light-sensing LED with Arduino (image 1) and learn how photoresistors (image 2) work in your projects. For this project, you'll need: I've recently posted a tutorial about this project on YouTube explaining everything you can read on this article. Or you can buy the following. Reading a light sensor with Arduino is an exciting and simple project that opens the door to various applications, from automated lighting systems to environmental monitoring.