Question

Why do concave mirror converge parallel beams of light, and convex mirror do not ?

Answer 1

Light rays converge as well as diverge. it depends upon the type of lens or mirror you pass it through. A concave lens or a convex mirror diverges the light whereas a convex lens or a concave mirror converges the light rays. The simple answer is that light travels in a straight line in any given medium. A medium could be anything light can pass through like air, vacuum, water, glass, plastic. Each medium has its own 'refractive index' which is a physical property of the material that varies the speed of light within a medium. Light travels slower in glass than it does in air for example. Light bending or refraction occurs as light passes the boundary of one medium into another. When viewing light from an object through a lens, that light passes from the object through air to the lens material and back into the air before reaching they observers eye. . Light rays entering the front convex or concave surface of a lens are refracted (bent) by the refractive index of the lens to a new path through the lens material. As light leaves the lens material it is bent again as it reenters the air. The extent that light rays bend depends on the lens material and the curvature of the lens surfaces.. Light entering a concave mirror is refracted toward a focal point on the other side of the lens. Light at the edges bends more than light passing through the center of the lens, however all rays converge at the focal point. If an observer were to place their eye just in front of the focal point the image would appear larger and in the same orientation. If an observer places their eye beyond the focal point the image appears inverted. Light entering a convex mirror is refracted away from a focal point making the image appear smaller.