Definitions Reflection Light – Self-Luminous ObjectNon Luminous ObjectConverging BeamDiverging BeamParallel beam Reflection of Light Diffuse Reflection Reflected Ray Incidence Ray Normal at the point of incidence Angle of Incidence Angle of reflection Virtual Image Real Image Parallax Concave Convex Pole Centre of Curvature Principal axis Focus/Focal Point Focal Length Refraction Refraction Refracted Ray Angle of refraction Refractive index of a medium Refractive index between two media Critical Angle Total Internal Reflection Optical Fibre