Refflection and Refraction

Reflection and refraction. In reflection the incidence light hits the mirror and reflects off if the mirror is smooth itll bounce of perfectly. The throwing back by a body or surface of light, heat, or sound without absorbing it. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density. Here are convex lens and concave lens. A convex lens goes out and a concave lens caves in. 

http://www.physicsclassroom.com/class/waves/Lesson-3/Reflection,-Refraction,-and-Diffraction