1. Light is an electromagnetic wave that vibrates perpendicular to its direction of propagation, making it a transverse wave.
2. Mirrors reflect light via the law of reflection, where the angle of incidence equals the angle of reflection. Plane mirrors form virtual upright images of the same size as the object, while curved mirrors can focus light.
3. Lenses refract light to form real or virtual images. Convex lenses are thicker in the middle and converge light rays to form an upright, magnified virtual image on the same side as the object.