1. LIGHT
LIGHT AND COLOR

2. LIGHT
A RANGE OF FREQUENCIES OF ELECTROMAGNETIC WAVES THAT STIMULATE THE RETINA OF THE EYE.
TRAVELS IN A STRAIGHT LINE IN A VACUUM OR UNIFORM MEDIUM

3. RAY THE STRAIGHT LINE PATH LED TO THE MODEL OF LIGHT AS A RAY.
RAY – A STRAIGHT LINE PATH OF A VERY NARROW BEAM OF LIGHT.
RAY OPTICS – USED TO STUDY THE WAY LIGHT TRAVELS, INCLUDING HOW IT IS REFLECTED AND REFRACTED.

4. SOURCES OF LIGHT LUMINOUS – OBJECTS THAT EMIT LIGHT
ILLUMINATED – OBJECTS THAT REFLECT LIGHT

5. LUMINOUS
STARS ARE LUMINOUS OBJECTS. THE CHEMICAL REACTIONS OCCURING WITHIN THE STAR GIVE OFF ENERGY.
SOME OF THAT ENERGY IS EMITTED IN THE FORM OF VISIBLE LIGHT.

6. ILLUMINANCE
ILLUMINANCE IS LIGHT INTENSITY OR THE AMOUNT OF LIGHT GIVEN OFF.
THE RATE LIGHT IS EMITTED IS CALLED LUMINOUS FLUX (P).

7. ILLUMINENCE
LIGHT WAVES MOVE AT THE SAME RATE IN ALL DIRECTIONS FROM THE ILLUMINATING OBJECT … A SPHERE SHAPE OF LIGHT
AS THE WAVES SPREAD OUT MORE AND MORE THE AMOUNT OF LIGHT HITTING AN OBJECT WILL BE LESS THE FARTHER FROM THE SOURCE IT IS LOCATED.

8. CALCULATING ILLUMINENCE
E – ILLUMINENCE, LUX
P – LUMINOUS FLUX, LUMEN
D – DISTANCE FORM SOURCE
E = P/4πd2

9. SPEED OF LIGHT THE SPEED OF LIGHT IS ACCEPTED AS 2.998 X 108 M/S
WE USE 3.0 X 108 M/S

10. DISPERSION OF LIGHT
ALL E-M WAVES TRAVEL AT 3 X 108 M/S IN A VACUUM. THEY TRAVEL SLOWER IN OTHER MEDIUM.
THE INDEX OF REFRACTION TELLS YOU HOW MUCH SLOWER.
THE INDEX OF REFRACTION IS DEPENDENT UPON THE WAVELENGTH OF THE LIGHT.

11. INDEX OF REFRACTION
IN MOST MATERIALS RED LIGHT TRAVELS FASTER THAN VIOLET LIGHT WHICH MEANS IT HAS A SMALLER INDEX OF REFRACTION.

12. DISPERSION
A SMALLER INDEX OF REFRACTION FOR THE RED LIGHT MEANS THAT IT WILL BEND AT A SMALLER ANGLE THAT THE VIOLET SO IT WILL SEPARATE FROM THE WHITE LIGHT FIRST. ORANGE WILL BE NEXT AND SO ON UNTIL A “RAINBOW” IS EVIDENT.

13. DISPERSION OF LIGHT
WHEN LIGHT IS DISPERSED IT IS DIVIDED INTO THE COLORS WE CALL THE VISIBLE SPECTRUM

14. LIGHT SPECTRUM
THE VISIBLE LIGHT SPECTRUM MOVES FROM RED TO VIOLET. IT GOES IN A SET ORDER.
RED
ORANGE
YELLOW
GREEN
BLUE
INDIGO (UNDER CONTENTION)
VIOLET

15. COLOR λ COLORS ARE ASSOCIATED WITH FREQUENCY. COLOR f VIOLET 400 nm
7.5 X 1014 Hz
GREEN
500 nm
6 X 1014 Hz
YELLOW
600 nm
5 X 1014 Hz
RED
700 nm
4.3 X 1014 Hz

16. COLORS RED HAS THE LONGEST VISIBLE WAVELENGTH
VIOLET HAS THE SHORTEST VISIBLE WAVELENGTH.
INFRARED IS LONGER THAN RED.
ULTRAVIOLET IS SHORTER THAN VIOLET.

17. COLOR
EACH COLOR REPRESENTS A SPECIFIC RANGE OF WAVELENGTH

18. MIXING COLORED LIGHT
WE KNOW FROM DISCUSSING DISPERSION, WHITE LIGHT SEPARATES INTO THE SPECTRUM – SO IT FOLLOWS THAT IF YOU MIX THESE COLORS OF LIGHT THEY WILL MAKE WHITE LIGHT.
IN FACT IT ONLY TAKES THREE COLORS TO MAKE WHITE LIGHT.

19. PRIMARY LIGHT COLORS
RED, BLUE AND GREEN, THAT IS WHY THEY ARE CALLED THE PRIMARY COLORS OF LIGHT
PRIMARY COLORS IN LIGHT ARE DIFFERENT THAN WHAT YOU LEARNED IN ART. WHAT YOU LEARNED IN ART WAS THE PRIMARY COLORS OF PIGMENTS.

20. SECONDARY COLORS
IF YOU MIX TWO PRIMARY COLRS OF LIGHT, YOU CREATE THREE DIFFERENT COLORS CALLED SECONDARY COLORS
RED + GREEN = YELLOW
GREEN + BLUE = CYAN
BUE + RED = MAGENTA

21. COMPLIMENTARY COLORS
EACH PRIMARY COLOR CAN BE PAIRED WITH ONE OF THE SECONDARY COLORS TO FORM WHITE LIGHT.
COMPLIMENTARY COLORS
EX: YELLOW IS RED + GREEN LIGHT IF YOU ADD BLUE IT WILL MAKE WHITE LIGHT SO BLUE IS THE COMPLIMENTARY COLOR TO YELLOW.

22. COMPLIMENTARY COLORS BLUE + YELLOW = WHITE RED + CYAN = WHITE
GREEN + MAGENTA = WHITE

23. FILTERS
FILTER BLOCK CERTAIN WAVELENGTHS WHILE ALLOWING OTHERS TO PASS THROUGH
A BLUE FILTER BLOCKS ALL WAVELENGTHS OTHER THAN THOSE IN THE BLUE RANGE OF THE SPECTRUM.

24. FILTERS A YELLOW FILTER ALLOWS RED AND GREEN
A RED FILTER ALLOWS ONLY RED
WHILE A GREEN FILTER ALLOWS ONLY GREEN
ADD A RED FILTER TO THAT AND NO LIGHT PASSES

25. PIGMENTS AND DYES
PIGMENTS AND DYES ABSORB CERATIN WAVELENTHS OF LIGHT AND REFLECT OTHERS.
THE COLOR THEY APPEAR IS DETERMINED BY THE COLORS THAT ARE REFLECTED.
EX: GRASS ABSORBED BLUE AND RED AND REFLECTS ONLY GREEN.
BLACK OBJECTS ABSORB ALL LIGHT
WHITE OBJECT REFLECT ALL LIGHT

26. QUESTION WHAT COLOR WOULD A RED BALL UNDER A GREEN LIGHT APPEAR?
BLACK, WHY?

27. ILLUMINATED OBJECTS OBJECTS THAT ARE ILLUMINATED REFLECT LIGHT
THE COLOR OF THE OBJECT DEPENDS ON WHICH WAVELENGTHS ARE REFLECTED.

28. ANGLE OF REFLECTION θ1 = θ2 DIAGRAM
ANGLE OF INCIDENCE ° ° ANGLE OF REFLECTION
θ1 = θ2

29. PIGMENT PRIMARY COLORS
THE PRIMARY COLORS IN PIGMENTS ARE THE ONES THAT ABSORB ONE COLOR OF LIGHT.
YELLOW PIGMENT ABSORBS BLUE AND REFLECT RED AND GREEN LIGHT.
PRIMARY PIGMENT COLORS ARE:
YELLOW, CYAN, AND MAGENTA

30. SECONDARY PIGMENT COLORS
COLORS CREATED BY MIXING TWO PRIMARY PIGMENTS.
YELLOW (ABSORBS BLUE)
+ CYAN (ABSORBS RED)
REFLECT ONLY GREEN
THE SECONDARY PIGMENT COLORS ARE: GREEN, RED AND BLUE

31. CLASSIFICATION OF MATERIALS
WE CLASSIFY MATERIALS BY THE WAY THEY REACT TO LIGHT.
TRANSPARENT
TRANSLUCENT
OPAQUE

32. TRANSPARENT
TRANSPARENT MATERIALS TRANSMIT LIGHT WITH LITTLE DISTORTION.
OBJECTS CAN BE SEEN CLEARLY THROUGH TRANSPARENT MATERIALS.
MOST LIGHT IS TRANSMITTED, SOME WILL BE REFLECTED, BUT VERY LITTLE WILL BE ABSORBED.

33. TRANSLUCENT MATERIALS TRANSMIT LIGHT WITH SIGNIFICANT DISTORTION.
OBJECTS CANNOT BE SEEN CLEARLY THROUGH TRANSLUCENT MATERIALS.
SOME LIGHT IS TRANSMITTED, SOME IS REFLECTED, AND SOME IS ABSORBED.

34. OPAQUE
MATERIALS DO NOT TRANSMIT LIGHT. ALL LIGHT IS EITHER REFLECTED OR ABSORBED.

35. REFRACTION OF LIGHT
LIGHT BENDS WHEN IT GOES FROM ONE MEDIUM TO THE NEXT.
THE SPEED OF LIGHT DEPEND ON ITS MEDIUM.
AS IT CHANGES FROM ONE MEDIUM TO THE NEXT ITS SPEED CHANGES CAUSING THE BEAM TO BEND AT THE BOUNDARY.

36. REFRACTION EACH MEDIUM HAS AN INDEX OF REFRACTION (n) NORMAL
ANGLE OF INCIDENCE
AIR
ANGLE OF REFRACTION GLASS

37. SOLVING FOR INDEX OF REFRACTION
THE INDEX AOF REFRACTION IS EQUAL TO THE SPEED OF LIGHT IN A VACUUM DIVIDED BY THE SPEED OF LIGHT IN THE SUBSTANCE.
Ns = C/Vs

38. THE AMOUNT LIGHT BENDS
THE AMOUNT THE LIGHT BENDS IS DETERMINED BY THE SPEED OF LIGHT IN THE REFRACTING MEDIUM.
Ni SIN θi = Nr SIN θr (CALLED SNELL’S LAW)
θi – ANGLE OF INCIDENCE
θr – ANGLE OF REFRACTION
THE ANGLES ARE MEASURED FROM THE VERTICAL. (THE VERTICAL IS CALLED THE NORMAL.)

39. Nr > Ni AND θr < θi
AS LIGHT MOVES FROM ONE MEDIUM TO ANOTHER ITS DIRECTION CHANGES OR IT BENDS BECAUSE ITS VELOCITY CHANGES.
IF THE REFRACTING MEDIUM HAS A HIGHER INDEX OF REFRACTION THAN THE INCIDENT MEDIUM, THE LIGHT IS GOING TO SLOW DOWN AND BEND AWAY FROM THE BOUNDARY AND TOWARD THE NORMAL.
THE ANGLE OF REFRACTION WILL SMALLER THAN THE ANGLE OF INCIDENCE.

40. Nr < Ni AND θr > θi
IF THE REFRACTING MEDIUM HAS A LOWERE INDEX OF REFRACTION THAN THE INCIDENT MEDIUM, THE LIGHT IS GOING TO SPEED UP ATER THE BOUNDARY.
THE LIGHT WILL BEND TOWARD THE BOUNDARY AND AWAY FROM THE NORMAL.
THE ANGLE OF REFRACTION WILL BE LARGER THAN THE ANGLE OF INCIDENCE.

41. CRITICAL ANGLE
WHEN THE LIGHT MOVES FASTER IN THE REFRACTING MEDIUM THAN IN THE INCIDENT MEDIUM SOMETHING DIFFERENT HAPPENS.
AS THE ANGLE OF INCIDENCE INCREASES, SO DOES THE ANGLE OF REFRACTION, BUT IT IS BIGGER THAN THE ANGLE OF INCIDENCE.

42. CRITICAL ANGLE
WHEN THE ANGLE OF REFRACTION GETS SO LARGE IT IS 90 DEGREES THE LIGHT DOES NOT REALLY ENTER THE MEDIUM BUT ITS MOVING ALONG THE SURFACE OF THE MEDIUM.
THIS IS CALL THE CRITICAL ANGLE
Ni SIN θi = Nr SIN 90
SIN θi = Nr/ Ni θi= CRITICAL ANGLE