The nature and propagation of light

1. THE NATURE AND
PROPAGATION OF LIGHT

4. OPTICS
• A branch of physics that deals with the
behavior of light and other electromagnetic
waves.

6. DISPERSION
• The separation of visible light into its different
colors.

10. Line of Sight
“In order to view an object, you must sight along
a line at that object; and when you do light
will come from that object to your eye along
the line of sight.”

11. Law of Reflection
“Once a normal to the surface at the point of
incidence is drawn, the angle of incidence can
then be determined. The light ray will then
reflect in such a manner that the angle of
incidence is equal to the angle of reflection.”

12. Law of Reflection
өi = өr
Where:
өi = angle of incidence
өr = angle of reflection

13. • The Law of Reflection is always observed
regardless of the orientation of the object.

14. • Rough surfaces also reflect light.

15. Specular Reflection
• Reflection off of smooth surfaces such as
mirrors or a calm body of water

16. Diffuse Reflection
• Reflection off of rough surfaces such as
clothing, paper, and the asphalt roadway

17. Application:
• Night Driving

18. Application:
• Photography

19. WHY IS AN IMAGE FORMED?

23. • An image is formed
because light emanates
from an object in a
variety of directions.
Some of this light
(which we represent by
rays) reaches the
mirror and reflects off
the mirror according to
the law of reflection.

24. Image Location
• is the location in space where all the reflected
light appears to diverge from.
• In the case of plane mirrors, the image is said
to be a virtual image.

27. Characteristics of Plane Mirrors
1. The image formed is VIRTUAL
2. Left-Right Reversal
3. Relationship between the object’s distance
from the mirror and the image’s distance to
the mirror. (They are equal)
4. The dimensions of the object is the same as
the dimensions of the image.

28. • The image has the same dimensions as the
object and is the same distance behind the
mirror as the object is in front of the mirror.

29. REFLECTION AND REFRACTION

33. Law of Reflection and Refraction

41. • If λ0 is the wavelength in a vacuum, the same
wave has shorter wavelength λ in a medium
with index of refraction n.

44. TOTAL INTERNAL REFLECTION
• Under certain circumstances, all of the
light could be reflected back from the
interface even though the material is
transparent.

45. • The angle of
incidence for
which the angle of
refraction is 90
degrees is called
the critical angle.

46. Where na > nb

47. Sample Problem
• Solve for the critical angle for a glass-
air surface with n= 1.52 for glass.

48. SEATWORK
½ c.w. DO NOT COPY THE QUESTIONS (SHOW COMPLETE SOLUTION)

49. 1. Light travels from air into a material
at an angle of incidence of 59°. If the
angle of refraction is 41°, what is the
index of refraction of the material?

50. 2. Solve for the critical angle for water
(nb = 1.33) on glass (na = 1.52).

51. 3. Light goes from benzene (n = 1.50)
into diamond (n = 2.42). If the angle
of incidence is 60 degrees, what is
the angle of refraction?