1. Seeing Things Plane Mirror Image Characteristics

2. Try printing your name on a piece of paper so that it can be easily read in a mirror. Image Characteristics

3. It’s hard but with practice you can print your name so that it looks something like this. Image Characteristics Emergency vehicles, like ambulances, use this characteristic so that they are easily recognized in rear view mirrors. Most people think mirrors flip the image left to right, or laterally invert it. But that’s not quite right.

4. Image Characteristics What happens if “Your Name” is read at the bottom of the mirror? Can you still read it easily? Try to write “ Your Name “ so that it can be easily read in a mirror. This will be next to impossible unless you know about a trick.

5. The Trick How to write your name so that it is more easily read in a mirror.

6. Recall - Image Location in Plane Mirrors 1)The distance from the object to the mirror is the same as the distance from the image to the mirror. 2)The line connecting the object and image intersects the mirror at 90 °.

7. Looking from the Side The distance of points on the object to the mirror is the same as that of corresponding points on the image to the mirror. The object and image appear to be flipped or folded about the mirror.

8. We use this knowledge of Folding About the Mirror of the object and image to easily write your name so that it can more easily be read in a mirror.

9. Start by printing “Your Name” on a piece of paper. Fold it as shown.

14. Trace your name through the folded paper. This is easier if you put the paper on a bright light source like a window or overhead projector.

15. Unfold the paper. You have laterally inverted your name. This inversion predicts how the image will appear in the mirror.

16. When placed beside a mirror, the inversion predicts how the image will appear in the mirror.

17. If you use the inversion of your name as the object, the image will be flipped back so that it is easily read in the mirror.

18. A similar trick can be used to fold your name so that it can be placed below the mirror.

19. Again fold as shown.

20. Again, fold as shown.

23. Once again, trace your name through the folded paper.

24. Unfold the paper. This time you have vertically inverted your name. This also predicts how the image will appear in the mirror if it is placed above or below.

25. When placed below a mirror, the inversion again predicts how the image will appear in the mirror.

26. If you use the inversion of your name as the object, the image will again be flipped back so that it is easily read in the mirror.

27. There is a more useful way of thinking about the image inversions. When the object is between the Eye-Brain and the mirror, …….

28. There is a more useful way of thinking about the image inversions. When the object is between the Eye-Brain and the mirror, the front edge of the object is flipped to the back edge of the image……..

29. There is a more useful way of thinking about the Image inversions. When the object is between the Eye-Brain and the mirror, the front edge of the object is flipped to the back edge of the image and the back edge of the object……..

30. There is a more useful way of thinking about the image inversions. When the object is between the Eye-Brain and the mirror, the front edge of the object is flipped to the back edge of the image This is called Front-Back Inversion. and the back edge of the object is flipped to the front edge of the image.

31. Still another way of looking at this is that the back of the object (black background)…… Front-Back Inversion

32. Still another way of looking at this is that the back of the object (black background) is flipped to the front of the image and vice- versa. Front-Back Inversion

33. Still another way of looking at this is, the back of the Object (black background) is flipped to the front of the Image and vice-versa. Front-Back Inversion

34. Still another way of looking at this is that the back of the object (black background) is flipped to the front of the image and vice- versa. The image is just what the back of the object would look like., Front-Back Inversion

35. What if Your Name is parallel or facing the mirror? Start with the object, “Your Name”, facing the Eye-Brain. Front-Back Inversion

36. What if Your Name is parallel or facing the mirror? The object, “Your Name”, is rotated so that it faces the mirror. Front-Back Inversion

37. What if Your Name is parallel or facing the mirror? The object, “Your Name”, is rotated so that it faces the mirror. Front-Back Inversion

38. What if Your Name is parallel or facing the mirror? The object, “Your Name”, is rotated so that it faces the mirror. Front-Back Inversion

39. What if Your Name is parallel or facing the mirror? “Your Name” is on the back of the object facing the mirror. Front-Back Inversion

40. What if Your Name is parallel or facing the mirror? The image in the mirror is actually Front-Back Inverted. The image is what the back of the object would look like if you could see through the object. The reason that the image is laterally inverted is because you inverted it that way in order to face the mirror.

41. In a mirror, the object of a right hand and its image both point to the right. Therefore, the image does not reverse left and right.

42. In a mirror, the object of a right hand’s thumb and its image both point up. Therefore, the image does not reverse up to down.

43. In a mirror, the object of a right hand pointing in results in an image pointing out. Therefore, the image does change In to Out, or Front to Back.

44. BUT, the image of a right hand looks like a left hand. In a plane mirror, RIGHT is changed to LEFT by changing IN into OUT.

45. Finally, the image in a plane mirror is called VIRTUAL. We usually see things because rays of light go from what we are looking at straight into our eyes. This applies to real objects as well.

46. Images. When light rays enter the Eye-Brain, it cannot tell where they actually come from.

47. Images When light rays enter the Eye-Brain, it cannot tell where they actually come from. The image only appears to be behind the mirror because of the way light reflects off the mirror.

48. A plain mirror can be treated like a window. The image is seen through this “window”.

49. Of course, mirrors are not windows. Mirrors are opaque. The only light rays that exist are those that reflect off the mirror. This is why images in plane mirrors are called VIRTUAL. No real rays of light can travel from the image to the Eye-Brain. They only appear to come from that direction because of the way light reflects off the mirror.

50. Review 1)Images in plane mirrors have the following characteristics: They are the same size as the object. They are Inverted Front to Back which makes them appear to be left/right or top/bottom inverted. They are located an equal distance from the mirror as the object is and the line connecting the object and image intersects the mirror at 90 °. They are virtual.

51. Review in Table Form SILT - Image Characteristics Review Table SizeSame InversionFront to Back LocationEqual to Object Distance, 90º Behind Mirror TypeVirtual

52. 2)Does a candle have to be in front of a mirror in order to form an image? Try It!

53. Both candles can form images. The “mirror” must be extended to find the location of the image for candle #2. It is there, but how must you look?

54. 3)Can all Eye-Brain observers see all images?? a) Show where the images are located.

55. 3) Show where the images are located. Both candles can form an image. The mirror must be extended to find the location of image #2.

56. 4)i. Which Eye-Brain can see the image of candle #1? C) D) & E) can see image #1. The mirror acts like a window. A straight line must exist between the Eye-Brain and image through the mirror.

57. 4)ii. Which Eye-Brain can see the image of candle #2? A) B) C) & D) can see image #2. The mirror acts like a window. A straight line must exist between the Eye-Brain and image through the mirror.

58. 5)What determines whether an Eye-Brain observer can see an image or not? Mirrors act like windows. A straight line through the mirror must exist between the Eye-Brain and image. Use the Applet described in the notes to review further.Applet