Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley PowerPoint ® Lectures for University Physics, Twelfth Edition – Hugh D. Young and Roger A. Freedman Lectures by James Pazun Chapter 34 Geometric Optics

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Objects, images, and light rays Light rays from a source will radiate in all directions, reflect from mirrored surfaces, and bend if they pass from a material of one index to another. Consider Figures 34.1, 34.2, and 34.3.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Constructing the image from a plane mirror I Following the light rays to form an image of an object. Consider Figure Consider Figure 34.5.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Constructing the image from a plane mirror II Consider Figure 34.6, below left. Consider Figure 34.7, below right. Images from a plane mirror show left/right reversal.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Reflections from a spherical mirror Images from a concave mirror change depending on the object position. Consider Figure Concave and convex mirror sign convention. Consider Figure

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Sign convention What is sign of image distance and radius of curvature? A. s’ > 0, R > 0 B. s’ > 0, R < 0 C. s’ 0 D. s’ < 0, R < 0

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Sign convention What is sign of image distance and radius of curvature? A. s’ > 0, R > 0 B. s’ > 0, R < 0 C. s’ 0 D. s’ < 0, R < 0

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The focal point and focal length of a spherical mirror The focal point is at half of the mirror’s radius of curvature. All incoming rays will converge at the focal point. Consider Figure

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Which of the following changes its focal length when it is immersed in water? Q34.1 A. a concave mirror B. a convex mirror C. a diverging lens D. all of the above E. none of the above

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Which of the following changes its focal length when it is immersed in water? A34.1 A. a concave mirror B. a convex mirror C. a diverging lens D. all of the above E. none of the above

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley A concave mirror with a radius of curvature of 20 cm has a focal length of Q34.2 A. 40 cm. B. 20 cm. C. 10 cm. D. 5 cm. E. answer depends on the index of refraction of the air around the mirror

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley A concave mirror with a radius of curvature of 20 cm has a focal length of A34.2 A. 40 cm. B. 20 cm. C. 10 cm. D. 5 cm. E. answer depends on the index of refraction of the air around the mirror

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley A system of rays may be constructed to reveal the image Rays are drawn with regard to the object, the optical axis, the focal point, and the center of curvature to locate the image. Consider Figure to view one such construct.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The convex spherical mirror I If you imagine standing inside a shiny metal ball to visualize the concave spherical mirror, imagine standing on the outside to visualize the concave spherical mirror. Consider Figure to introduce the convex spherical mirror.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley A graphical method for mirrors On slide 11, we hinted at a graphical formalism using the object, the center of curvature, the focal point, and the mirror plane. Consider Figure to view the entire formalism.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Thin lenses I The converging lens is shown in Figure Note symmetrical focal points on either side of the lens. Figure uses the same ray formalism as we used with mirrors to find the image.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Thin lenses II Figure at bottom left illustrates a diverging lens scattering light rays and the position of its second (virtual) focal point. Figure illustrates some assorted common arrangements of lens surfaces. Follow Example 34.8.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Q34.8 A. only the object’s upper half will be visible in the image. B. only the object’s lower half will be visible in the image. C. only the object’s left-hand half will be visible in the image. D. only the object’s right-hand half will be visible in the image. E. the entire object will be visible in the image. An object PQ is placed in front of a converging lens, forming a real image P´Q´. If you use black paint to cover the lower half of the lens,

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley A34.8 A. only the object’s upper half will be visible in the image. B. only the object’s lower half will be visible in the image. C. only the object’s left-hand half will be visible in the image. D. only the object’s right-hand half will be visible in the image. E. the entire object will be visible in the image. An object PQ is placed in front of a converging lens, forming a real image P´Q´. If you use black paint to cover the lower half of the lens,

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Graphical methods for lenses Figure applies to lenses the same ray-tracing method we used for mirrors.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Magnifying lens A magnifying lens with focal length 15cm is used to magnify an ant which is 10 cm away. Draw a ray diagram of this situation Calculate the distance the image is away from the lens How big does the 2 mm long ant appear?

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The camera A clever arrangement of optics with a method to record the inverted image on its focal plane (sometimes film, sometimes an electronic array, it depends on your camera).

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The eye—vision problems When the lens of the eye allows incoming light to focus in front of or behind the plane of the retina, a person’s vision will not be sharp. Figure (at right) shows normal, myopic, and hyperopic eyesight.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Vision correction—examples Follow Example 34.13, illustrated in Figure in the middle of the page. Follow Example 34.14, illustrated in Figure at the bottom of the page.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The microscope Optical elements are arranged to magnify tiny images for visual inspection. Figure presents the elements of an optical microscope.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The astronomical telescope Optical elements are arranged to magnify distant objects for visual inspection. Figure presents the elements of an astronomical telescope.

Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley The reflecting telescope Optical elements are arranged to reflect collected light back to an eyepiece or detector. This design eliminates aberrations more likely when using lenses. It also allows for greater magnification. The reflective telescope is shown in Figure