Millions of light rays reflect from objects and enter our eyes – that ’ s how we see them!

1. or Millions of light rays reflect from objects and enter our eyes – that’s how we see them! When we study the formation of images, we will isolate just a few useful rays:

2. measured fromthe normal A line  to the surface at the point of incidence i= r Law of reflection Reflection i = incident angle r = reflected angle

3. Plane (flat) mirrors object mirror image To locate the image: 1) Draw 2 different rays leaving the same point. 2) Draw their reflections. 3) Extend the reflections behind the mirror. 4) The point where they meet locates the image.

4. Which type do you get from a plane mirror ? There are two different types of images: Real image Light rays actually meet at that point Virtual image Light rays only appear to emanate from that point For all plane mirrors: • Image is upright • Image is same size as object • object’s distance from mirror (do) = image’s distance from mirror (di) • Right and left are reversed

5. do di

6. When mirror surfaces are curved instead of flat, strange things happen……

7. Spherical Mirrors concave side convex side

8. Concave Spherical Mirrors principle axis (axis of symmetry) C R Parallel Rays (distant object): C F f f = ½ R Concave mirror C = Center of Curvature R = Radius of Curvature F = focal point f = focal length

9. Ray #1: Parallel to the axis Relects through F Ray #2: Through F Reflects parallel to axis Ray #3: Through C Reflects back on itself Locating Images: Ray Tracing The use of 3 specific rays drawn from the top of the object to find location, size, and orientation of the image For a Concave Mirror:

15. Results: Ray Tracing for concave mirrors C C C Object is behind C: Image is always real, smaller, and inverted Object between C and F: Image is always real, larger, and inverted F F F Object between F and mirror: Image is always virtual, larger and upright Ex: Makeup mirror

16. Mirror Applications • Concave mirrors: Magnification

17. Mirror Applications • Concave Mirrors: Telescopes

18. Mirror Applications • Concave Mirrors: Flashlights • (light at focal point)

19. Convex Spherical Mirrors C C R Parallel Rays (distant object): Since it’s behind the mirror F f f = -½ R Convex mirror

20. For a Convex Mirror: Ray #1: Parallel to the axis / Relects as if it came from F Ray #2: Heads toward F / Reflects parallel to axis Ray #3: Heads toward C / Reflects back on itself

21. C Wherever the object is: Image is always virtual, smaller and upright Car side mirrors • “Objects in mirror are closer than they appear” • What type of mirror? • Why would these be used in cars? F Results: Ray Tracing for convex mirrors (draw in the 3 rays for practice)

22. Mirror Applications • Convex Mirrors: Widen range of sight

23. The Mirror Equation works for both concave and convex mirrors: C C f f do do + for in front of mirror (real) F F - for behind mirror (virtual) The Mirror Equation OR f = mirror’s focal length (+ for concave, - for convex ) do = distance between object and mirror di = distance between image and mirror

24. The Magnification Equation m is + if the image is upright m is - if the image is inverted m>1 if the image is larger than object m<1 if the image is smaller than object What about the size of the image ?? ho = height of object hi = height of image m = magnification = hi /ho

25. Ex: 15 cm 80 cm The mirror’s radius of curvature is 60 cm. Find the location, size and orientation of the image of the cat.

26. Ex: 15 cm 80 cm The mirror’s radius of curvature is 60 cm. Find the location, size and orientation of the image of the dog.