A free original RRB Group D optics workbook. Learn reflection and mirror images, refraction and thin lenses, the human eye, dispersion and atmospheric effects. Both languages contain complete teaching, worked examples, lesson checks and explained review answers. The separate review is untimed learning practice, with one mark per question, no negative marking and no pass cutoff. It is not a full CBT simulation or complete General Science course; heat, sound and other topics remain outside this workbook. Diagrams state their paraxial or conceptual model assumptions.