Mirrors and Lenses

Pinholes A ________ can be used to form an image without a lens or mirror. pinhole Light rays from point source screen

Image formation with a Pinhole camera Light source Dark room = Camera Image is _______ if pinhole is larger Image is ________ if pinhole is smaller Image is __________ is pinhole is smaller fuzzy sharper dimmer

We can use the _____________. How does light interact with pinholes? How does light interact with lenses? ___________ How does light interact with mirrors? We can use the _____________. Refraction Reflection photon model

Mirrors Flat Concave Convex

Angle of incidence = Angle of reflection The Law of Reflection Angle of incidence = Angle of reflection In other words, light gets reflected from a surface at the same angle it hits it. The same !!!

Clear vs. Diffuse Reflection Smooth, shiny surfaces have a clear reflection: Rough, dull surfaces have a diffuse reflection. Diffuse reflection is when light is scattered in different directions

The Law of Reflection For reflection the _____________ qi equals the _______________ qr: qi = qr incident angle reflected angle The angles are measured relative to the _________, shown here as a dotted line. normal

Forming Images with a Plane Mirror A mirror is an object that reflects light. A _______ mirror is simply a flat mirror. Consider an object placed at point P in front of a plane mirror. An image will be formed at point P´ behind the mirror. do = distance from object to mirror di = distance from image to mirror ho = height of object hi = height of image hi ho do di For a plane mirror: do = -di and ho =hi

Images An image is formed at the point where the rays of light leaving a single point on an object either _________ intersect or from where they ________ to originate. actually appear

Images If the light rays actually do intersect, then the image is a __________. If the light only appears to be coming from a point, but is not physically there, then the image is a _____________. real image virtual image

Spherical Mirrors A _________ _______ has a surface shape with radius of curvature R. There are two types of spherical mirrors: _______ and _______. spherical mirror ________ concave concave convex ________ convex

Focal Point When ________ rays (e.g. rays from a distance source) are incident upon a spherical mirror, the reflected rays ________ at the _________ F, a distance R/2 from the mirror. parallel intersect focal point For a ________ _______, the focal point is in front of the mirror (_____). concave mirror real

Focal Point For a ____________, the focal point is behind the mirror (________). convex mirror The incident rays ______ from the _______ _______, but they trace back to the focal point F. diverge virtual convex mirror

Focal Length The _______________is the distance from the surface of the mirror to the focal point. It can be shown that the focal length is half the radius of curvature of the mirror. Sign Convention: the focal length is negative if the focal point is behind the mirror. For a concave mirror, f = ____ For a convex mirror, f =  ___ (R always +) focal length (f) ½ R ½ R

Lenses Concave Convex Refraction

Reflection and Refraction When a light ray travels from one medium to another, part of the incident light is _________ and part of the light is _____________ at the boundary between the two media. The transmitted part is said to be __________ in the second medium. reflected transmitted refracted incident ray reflected ray refracted ray

Red Light Red Light Red Light

Lenses Light is reflected from a mirror. Light is __________ through a lens. refracted

Focal Point The ___________ of a lens is the place where parallel rays incident upon the lens ________. focal point converge _______________ Converging lens ______________ Diverging lens

Focal Length

http://www. physics. odu http://www.physics.odu.edu/hyde/Teaching/Spring04/Lectures/318,1,Chapter 26: Geometrical Optics