Section 5.3 Images in Curved Mirrors 1

 Concave mirrors have a reflecting surface that curves inward like the inside of a spoon.  Some common uses: ◦ Shaving and makeup mirrors ◦ Reflectors in headlights ◦ Dentist mirrors 2

 Like plane mirrors, curved mirrors reflect light according to the law of reflection.  However, because concave mirrors are curved, they reflect in a certain way – they will converge. 3

 Concave mirrors can produce many different kinds of images. According to SPOT: ◦ Size – same, smaller, or larger. ◦ Position – same, closer, or farther away. ◦ Orientation – upright or inverted. ◦ Type – real or virtual  The image characteristics depend on where you place the object in front of the mirror. ◦ We will look at 3 different cases. 4

 Before we determine the image characteristics for concave mirrors you need to know some key parts of the ray diagram. ◦ Principal Axis – A line that is normal (perpendicular) to the center of a mirror. ◦ Vertex – The point at which the principal axis meets a mirror. ◦ Focal Point – The point at which converging light rays meet. Focal point Vertex Principal Axis 5

 When drawing ray diagrams, there are 3 main rules you must follow: ◦ Draw an incident ray traveling parallel to the principal axis. It will reflect through the focal point. ◦ Draw an incident ray passing through the focal point on the way to the mirror. It will travel parallel to the principal axis upon reflection. ◦ Draw an incident ray travelling to the vertex. It will reflect back at the same angle (relative to the principal axis) with which it entered the mirror (Law of Reflection). 6

 Object Between the Focal Point and the Mirror Image Properties Size Position Orientation Type 7

 Object Between the Focal Point and Two Times the Focal Point Image Properties Size Position Orientation Type 8

 Object Beyond Two Times the Focal Point Image Properties Size Position Orientation Type 9

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 A mirror that is curved outward, like the outside of a bowl, is called a convex mirror.  Common Uses: ◦ Security mirrors in stores ◦ Sunglasses ◦ Side mirrors on vehicles 11

 The curved surface of a convex mirror causes light rays to travel away from each other, or diverge.  These rays will never meet in front of the mirror as they do in concave mirrors.  However, if you extend the rays behind the mirror, they will intersect at the focal point, F. 12

 When drawing ray diagrams for concave mirrors, the image depended on where you put the object with reference to the focal point.  In convex mirrors, since the focal point is behind the mirror there is only one case – the object in front of the mirror! 13

 Object in Front of the Mirror Image Properties Size Position Orientation Type 14

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 P.209: #2, 10, 12, “Pause and Reflect”  Common Place Book: ◦ Definitions: “Key Terms” on p.196. ◦ Tic-Tac-Toe:  For anyone wanting to complete the case study option, read, summarize, and answer the questions on p.208. The article is called “Curved Surfaces Collect Solar Energy”. 16