Ch. 22 Sec. 3 Reflection & Mirrors Unit 4 Waves Ch. 22 Sec. 3 Reflection & Mirrors

Reflected Light Reminder… reflection is when a wave strikes a surface & bounces off reflected light = an image light obeys the law of reflection involves: 1) the normal 2) angle of incidence 3) angle of reflection

Parts of the Law of Reflection normal - an imaginary line perpendicular to the surface where light rays strike angle of incidence - created by the incoming light & the normal angle of reflection - created by the reflected light & the normal

Law of Reflection law of reflection - angle of incidence = angle of reflection (no matter what surface is reflecting the light)

Reflection from Rough Surfaces scattering - when light traveling in one direction is sent in many directions occurs when light is reflected off a rough surface OR when light encounters small particles (dust)

Reflection from Surfaces Rough Surfaces Smooth Surfaces reflected light goes in many directions creating a diffuse reflection reflected light goes in a single direction creating a regular reflection

Reflections from Mirrors reflections from a plane mirror (flat) are… reversed (left & right) seem to come from behind the mirror

Reflections from Mirrors Convex Mirrors Concave Mirrors convex mirror - surface is curved outward causes light rays to spread out (diverge) can view a larger area used for security mirrors & side mirrors in cars concave mirror - surface is curved inward causes light rays to come together (converge) used in headlights & flashlights

Optical Axis optical axis - an imaginary line that is perpendicular to the center of a convex or concave mirror

Concave Mirror Images IF incoming light is parallel to the optical axis, all light reflected from a concave mirror passes through the same point = focal point (distance from this point to the center of the mirror = focal length) IF an object is beyond the focal point… the image will be upside down (inverted) IF an object is b/w the mirror & the focal point… the image will be upright

Convex Mirror Images LIKE a plane mirror… UNLIKE a plane mirror the image in a convex mirror seems to be behind the mirror the image is always upright UNLIKE a plane mirror (& a concave mirror)… the image in a convex mirror is always smaller than the object