These basic electronics slides explains semiconductors, N-Type Silicones, P-Type Silicones, Diodes, Water analogy of diodes, How diodes works and how it does not also its applications, Half wave rectifier and full wave rectifiers, AC2DC Power supply, Transistors, and transistor types, Optoelectronics, LEDs, Photoresistors, Solar cells, what is phototransistors and how they works are explained shortly.
Combined Slides 
Relevant: Basic Electronics UOS Past Papers