2 air water As light reaches the boundary between two media, its energy is partially reflected back andpartially transmitted into the new medium.The amount that is reflecteddepends on the types of materials andthe angle of incident rays.airwater
3 Laws of Reflection First Law Second Law The angle of incidence, i, is equal to the angle of reflection, r.nirSecond LawThe incident and reflected rays,and the normal, are coplanar.
4 Images formed by mirrors and lenses may be classified as real or virtual.Real Imageformed by actual rays of converging lightVirtual Imagenot formed by actual rays of converginglight, but from where the rays of lightappear to come (diverging light rays)
5 Plane Mirror Images 1. virtual 2. upright 3. same size as object Images formed by plane mirrors are always:1. virtual(virtual images are always behind mirrors)2. upright(virtual images are always upright)3. same size as object(if the image is larger or smaller, the mirror isn’t flat)4. front and back are reversed(some say “left and right”)5. located as far behind the mirroras the object is in front
7 Click here and here to view simulations of light rays reflecting from a plane mirror.View reflection from two plane mirrorshere and here.Play a game here to test your skill.
8 Curved Mirrors Terminology center of curvature - C; the center of the original sphereradius of curvature - r;distance from center of curvature to the mirrorvertex - V; the center of the mirrorprincipal axis - a line through C and Vprincipal focus - F; the point on theprincipal axis where light rays paralleland close to the principal axis converge;or from where they appear to divergefocal length - f; distance from V to F
9 Ray Diagrams Concave (Converging) Mirrors rays parallel and close to the principalaxis reflect through the focus2. rays passing through the focus reflectparallel to the principal axis3. rays passing through the center ofcurvature reflect straight back alongthe incident pathC F
10 Convex (Diverging) Mirrors 1. rays parallel and close to the principalaxis reflect away from the focus2. rays heading toward the principal focusreflect parallel to the principal axis3. rays heading toward the center ofcurvature reflect straight back alongthe incident pathF C
11 Click here to view these three rays that are important in the formation of images in concave (converging) and convex (diverging) mirrors.Also view reflectionfrom curved mirrorshere, here,and here.
12 di/do = si/so 1/f = 1/do + 1/di Mirror Equation Magnification Diverging rays must be extended as dotted linesbehind the mirror in order to locate some images.Mirror EquationMagnificationdi/do = si/so1/f = 1/do + 1/dif = focal length; positive for convergingmirrors, negative for diverging mirrorsdo = object distance; usually positivedi = image distance; can be positive or negativeso = object size (height)si = image size (height)
13 Images formed by concave (converging) mirrors may be: 1. real, virtual, or non-existent2. upright or inverted3. reduced, enlarged, or same size4. in front or behind the mirrorLearn more about concave mirror images here.The image properties depend on theobject’s location with respect to themirror, focus, and center of curvature.
14 object is beyond the center of curvature: image is real, inverted, and reducedobject is on the center of curvature:image is real, inverted, and the same sizeobject between center of curv. and focus:image is real, inverted, and enlargedobject is on the focus:no image; rays reflect parallelobject is inside the focus:image is virtual, upright, and enlarged
15 Learn more about characteristics of convex mirror images here. Images formed by convex (diverging) mirrors are always:1. virtual2. upright3. reduced4. located behind the mirror between thevertex and focus
16 General Image Trends real images are always inverted virtual images are always uprightreal images are always in frontof the mirrorvirtual images are alwaysbehind the mirrornegative image distance meansvirtual imagepositive image distance meansreal image