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Home , Curved mirror, Lens, Thin lens

LECTURE 17 AND THIN EQUATION

Instructor: Kazumi Tolich Lecture 17

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¨ 18.6 formation with spherical mirrors ¤ Concave mirrors ¤ Convex mirrors

¨ 18.7 The thin-lens equation ¤ Sign conventions for and mirrors 18.6 Image formation with spherical mirrors

¨ Spherical mirrors (concave mirrors and convex mirrors) can be used to form . Quiz: 18.6-1

4 18.6 Concave mirrors

¨ The special rays for a concave : 18.6 Concave mirrors

¨ For the trace, incoming rays are drawn as if they are reflect off the mirror plane, not off the curved surface of the mirror.

¨ The image is real if rays converge at the image point. 18.6 Convex mirrors

¨ The special rays for a convex mirror: 18.6 Convex mirrors

¨ Diverging rays appear to diverge from the . 18.7 The thin-lens equation & Sign conventions for lenses and mirrors

¨ The thin-lens equation (for thin ¨ , �: lenses and mirrors): ¤ + for a converging lens or a concave mirror ¤ − for a diverging lens or a convex mirror 1 1 1 ¨ , �: + = ¤ + for upright image � � � ¤ − for inverted image ¨ Image distance, � : ¤ + for a real images ¤ − for a virtual images

¨ Object distance, �: ¤ + always Quiz: 18.7-1 through 18.7-4

10 Demo: lens equation applied for a lens

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¨ Image Formation ¤ Demonstration of a double convex lens forming an inverted and diminished or enlarged image. n + = n + = , where � is the distance between the source and the screen. ± n � = Quiz: 18.7-5 Example: 18.7-1 (Knight P18.27, modified)

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¨ A dentist uses a to view the back side of teeth on the upper jaw. Suppose she wants an erect image with a magnification of 2.0 when the mirror is 1.2 cm from a tooth. (Treat this problem as though the object and image lie along a straight line.) A. What is its focal length? B. Is it a convex or concave mirror?