1. Lenses
© D Hoult 2008

2. When light goes through glass (or any other transparent substance), its speed changes

3. When light goes through glass (or any other transparent) substance, its speed changes
This can cause it to change its direction of motion

4. When light goes through glass (or any other transparent) substance, its speed changes
This can cause it to change its direction of motion
The change in direction is called refraction of light

31. image

32. real
image

33. By calculation

34. By calculation 1 1 1 = + f u v

35. By calculation 1 1 1 = + f u v 1 = v

36. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u

37. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm

38. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm
u = 5 cm

39. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm
u = 5 cm 1 1 1 _ = v 3 5

40. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm
u = 5 cm _ 1 1 1 5 3 _ = = v 3 5 15

41. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm
u = 5 cm _ 1 1 1 5 3 _ = = v 3 5 15
Therefore v =

42. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 3 cm
u = 5 cm _ 1 1 1 5 3 _ = = v 3 5 15
Therefore v = 7.5 cm

51. image

52. virtual
image

53. By calculation

54. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u

55. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm

56. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm 1 1 1 _ = v 5 3

57. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm _ 1 1 1 3 5 _ = = v 5 3 15
Therefore v =

58. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm _ 1 1 1 3 5 _ = = v 5 3 15
Therefore v = cm

59. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm _ 1 1 1 3 5 _ = = v 5 3 15
Therefore v = cm
the negative tells us

60. By calculation 1 1 1 = + f u v 1 1 1 _ = v f u
f = 5 cm
u = 3 cm _ 1 1 1 3 5 _ = = v 5 3 15
Therefore v = cm
the negative tells us
that the image is virtual