Working principle of LEDs and why they are made from semiconductors. A quick guide on semiconductors and how doping can change them. More discussion here- http://devender-maun.blogspot.com/2015/03/how-leds-work-and-short-guide-on.html
Discussion on how do solar cells work? Why semiconductors are used in solar cells and explanation of photoelectric effect? For more details and schematics check this link: http://devender-maun.blogspot.com/
Discussion on why various objects have different color and fundamental mechanisms by which colors are produced. We discuss Rayleigh scattering, electronic transitions and concepts of absorption and reflection.