1. Color
Color is light's version of pitch i.e. its how the eye perceives the
frequency of the electromagnetic radiation between 4.3 x 1014 Hz
and 6.7 x 1014 Hz
When a stove element is turned on high we notice that it starts to glow
"red" hot
The radiation from the stove is such that the cells in the retina are
stimulated. Objects that glow "white" hot give off radiation over the
whole visible spectrum.

3. If white light is passed through a prism the colors of the visible
spectrum are observed. This process is called dispersion.

4. Chromatic Aberration
Since each color has a different wavelength, they are refracted
different amounts. The indices of refraction quoted earlier were
actually averages for all the colors.

5. Depends on the combined effect of all its emitted wavelengths.
The color of a source of light
Depends on the combined effect of all its emitted wavelengths.

6. Depends on the color of light it reflects.
The color of an illuminated object
Depends on the color of light it reflects.
IT IS IMPORTANT TO NOTE THAT, FOR ANY GIVEN OBJECT, THIS IS
NOTALWAYS THE SAME.

7. Depends on the color of light it transmits
The color of a transparent object
Depends on the color of light it transmits
Filters selectively absorb and transmit different colors.

8. ROYGBIV Newton formally called the seven colors of the rainbow
ELEMENTARY COLORS
Newton formally called the seven colors of the rainbow
the elementary colors.
ROYGBIV

9. The three elementary colors that produce white light when
PRIMARY COLORS
The three elementary colors that produce white light when
combined are called the primary colors
RED, GREEN, and BLUE.

10. COMPLIMENTARY COLORS
Any two colors that combine to produce white are complimentary.
YELLOW & BLUE = WHITE
CYAN & RED = WHITE
MAGENTA & GREEN = WHITE

11. PRIMARY PIGMENTS
Mixing paints or pigments is a subtractive process opposite
to mixing colors.
The primary pigments mixed in equal quantities produce black.
The primary pigments are
YELLOW, CYAN, and MAGENTA.

12. COLOR VISION
The Young- Hemholtz Theory of
color vision suggests that the
retina has three different types
of cone shaped cells on the retina,
each sensitive to one of the primary
colors.
When light enters the eye these cones will be stimulated depending
on the color of the light. e.g. a banana would stimulate only the red
and green cones.

13. COLOR BLINDNESS
An eye disorder, usually inherited, caused by a disproportionate
number of one or more of the color sensitive cone cells.
Most common is red-green.
e.g. a banana should stimulate the red
and green cones equally but a person
lacking in green cones would perceive
the banana as slightly orange since the
brain receives more red stimulus
than green.

14. COLOR TELEVISION
Three "electron" guns shoot electrons at a
Phosphorescent screen that has hundreds of rows
of red, green, and blue filters

16. RAINBOWS
Rainbows are usually created in the eastern sky after an
afternoon thunder shower.
White light from the sun enters the raindrops and disperses,
partially reflects on the opposite side and is redirected towards
the ground where an observer views the rainbow that forms a
semi-circle.
Because of the path the light takes as it refracts in the raindrop,
all observers see the rainbow in a slightly different place in the sky.
Sometimes light entering the bottom of the raindrop can reflect
internally twice and produce a secondary rainbow that is higher
in the sky and much less intense.

17. http://online. cctt. org/physicslab/content/applets/rainbow/rainbo_z

23. COLOR OF THE SKY AND OTHER RELATED STUFF
When the white light from the sun passes through the
atmosphere, the colors are scattered (diffracted) by
dust, water, etc.
The red light, being the longest wavelength, is scattered
the least and the blue is scattered the most.
The sky takes on a blue color while the sun appears yellow.

26. At sunset the light has to pass through more atmosphere
because of the angle
more of the green is scattered and the sun appears
orange or reddish orange depending on the humidity,
dust, smoke, of the air

29. Clouds
scatter most of the light that passes through making
them appear white if viewed from above or below if they
are very thin
grey if they are medium thickness
black if they are thunder cloud thick

32. SPECTROSCOPY
The science of studying the spectrum produced by
light sources
A device for doing this is called a spectroscope. Light is
passed through a narrow opening and the light diffracts,
each color a different amount due to the different
wavelengths

33. Emission Spectra
produced by luminous sources
a. continuous spectra
produced by incandescent solids, liquids and
gases under high pressure
b. bright-line spectra
produced by gases under low pressure
The bright-line spectrum produced by each
gas is unique

35. Absorption Spectra

36. Note that the absorption spectrum is like a negative of the
emission spectrum for each element
Emission Spectra
Absorption Spectra

37. Fraunhofer Lines (Solar Spectrum)
The chemical composition of the Sun can be determined
By analysing the Sun’s Absorption Spectrum.
The lines were discovered by Joseph Fraunhofer in 1814

39. Doppler Effect for Light
Since light is a wave like sound, the frequency will shift if
the source and observer move relative to each other.
If the source is moving away, the light is shifted towards the
low frequency end of the spectrum i.e. Red-Shifted
If the source is moving towards, the light is shifted towards
the high frequency i.e. Blue-Shifted

41. Big Bang Theory
In 1924, Edwin Hubble discovers a galaxy outside Milky Way
Also noted that light from distant galaxy was Red-Shifted which
means that galaxy is moving away.
Further discoveries, showed that
more distant galaxies are even more
Red-Shifted i.e. they are moving
faster.

42. The further away the galaxy is the further back in time
we are looking
The Big Bang is the results
of these observations.
In 1927 George LeMaitre
proposed that the Universe
expanded from a single point.
Current estimates have the
Universe at 13.7 Billion years