This document provides an overview of key concepts in ray optics, including: 1. Refraction is the change in direction of light when passing from one medium to another. Snell's law describes the relationship between angles of incidence and refraction. 2. Total internal reflection occurs when light passes from an optically dense to a rare medium at an angle greater than the critical angle. 3. Spherical lenses use the lens maker's formula and thin lens equation to determine image location based on the object position and the lens's focal length and refractive index. 4. Linear magnification is the ratio of image size to object size, and depends on the focal length and positions of the object and image.