1. Chapter 18-1 Mirrors

2. Plane Mirror a flat, smooth surface light is reflected by regular reflection rather than by diffuse reflection Light rays are reflected with equal angles of incidence and reflection.

3. Produces a virtual image which appears to be an equal distance behind the mirror. With a virtual image, the light rays do not actually converge on the point where the image appears. The object and the image have the same size. They are pointing in the same direction, so the image is an erect image. Left and right are reversed which is to say “the front and back of the image are reversed.” Plane Mirror

4. If you blink your right eye, your mirror image left eye blinks back at you:

5. Concave Mirrors A concave mirror reflects light from its inner, (“caved in”) surface. The principle axis is the straight line perpendicular to the surface of the mirror at its center. The focal point is the point where all rays parallel to the principal axis meet. It is half the distance between the mirror and the center of curvature (C). If you point the principal axis of a concave mirror at the sun, all the rays (which are parallel to each other—at “infinity”) will be reflected through the focus The distance from the focal point to the mirror along the principal axis is the focal length, f, of the mirror.

6. Real vs Virtual Images Real Image: the rays actually converge and pass through the image it can be seen on a piece of paper Virtual Image: The rays do not converge at the location of the virtual image The virtual image cannot be projected on a screen

7. How to draw Ray Diagrams: Draw the mirror, principal axis, a vertical line where the principal axis touches the mirror, the image, the focal point (F) and the center of curvature (C). Ray 1 (the parallel ray) is from the object to the mirror parallel to the principal axis. The reflected ray goes through the focal point Ray 2 (the focus ray) is from the object through the focal point. The reflected ray is parallel to the principal axis Where Ray 1 and Ray 2 intersect is the location of the image.

8. Possible scenarios for Concave Mirrors Object Image

9. Lens/mirror equation: “If I do I die.” f = focal length d o = distance of object from mirror d i = distance of image from mirror

10. Magnification the ratio of the size of the image, h i, to the size of the object, h o or

11. b. How high is the image?

12. Virtual Images Formed by Concave Mirrors

13. Image defect in Concave Mirrors Spherical aberration Parallel Incident Light from outer edge of spherical mirror fails to focus at a point Fix: Parabolic mirror

14. Convex Mirrors Convex mirrors do not form real images. Images are reduced in size and so appear far away “Fisheye lens” the image is small (reduced) but wide ranging (enlarged) field of view; upright image, virtual, reduced (images seem farther away) Good for security mirrors & rearview mirrors in cars A convex mirror is a spherical mirror that reflects light from its outer surface. Rays reflected from a convex mirror always diverge. Focal length, f, is a negative number (because F is behind the mirror) di is negative because the image is behind the mirror

15. Problem from Opening Page of Chap 18 in Textbook Four Butterflies but only one is real. Identify the images and the shape of lenses that produced them:

17. End 18-1