Download wvwphysics

Name________________________
Physics
Chapter 16 - Light
Light is an __________________________wave .
The frequencies of the light wave stimulate the retina of the eye. The eye can
detect light that is emitted from a source or reflected by an object.
The visible spectrum of light has wavelengths that range from:
_________________________________ to ______________________________
The visible spectrum is a range of color from:
___________________________________________________________________
The respective frequencies range from:
____________________________Hertz to __________________________Hertz
Light with wavelengths longer than red light is called
______________________waves followed by microwaves, radio waves, and TV waves.
Light with wavelengths shorter than violet light is called
____________________________waves followed by X-rays, and Gamma rays.
1
Name________________________
Physics
Chapter 16 – Light
The speed of light waves is constant.
V light = 299, 792,458 m/s =
c = 3 x 10 8 m/s in a vacuum
c = wavelength x frequency
(as the wavelength gets shorter, from red to violet, the frequency gets higher.
This is called an inverse relationship.)
E = mc2 (the c in this expression represents the speed of light)
Example:
Light takes 1.28 s to travel from the moon to the earth. What is the distance
between the earth and the moon?
2
Name________________________
Physics
Chapter 16 – Light
Light waves have a straight line path. As a result the wave is represented as a ray,
The study of light is called _________________________________.
Ray diagrams are used to study how light is REFLECTED and REFRACTED.
Draw a ray diagram to represent reflection and refraction.
Reflection
Refraction
3
Name________________________
Physics
Chapter 16 – Light
Sources of Light
A body that emits light is a __________________________________body. The rate at
which light is emitted from a ________________________ body is called the
__________________________________ (
)
and is measured in
_____________________________ (
)
(a 100 watt bulb emits approximately 1750 lumens)
A body that reflects light is a(n)________________________________body. The
amount of light that reaches a surface is called
_________________________________________ (
)
and is measured in __________________________per square meter also called a
___________________________________ (
)
Light falling on a surface is dependent upon:
1. The intensity of the light source.
2. Distance the light source is away from the surface.
_______________________ ( ) is directly proportional to __________________ ( )
Is inversely proportional to ________________( )
The formula for _________________________________ is:
If the distance is doubled, ____________________ is reduced by ________________.
If the distance is tripled, _____________________ is reduced by ________________.
If the distance is cut in half, __________________ is increased by _______________.
4
Name________________________
Physics
Chapter 16 – Light
A __________________________ (
) measures _______________
__________________________ ( ) and is referred to as candle power.
1.5 ______________ = 19 lumens
1 ___________ = ______________lumens
The formula for Luminous Intensity is:
The _____________________units are the SI units for measuring light intensity.
List all formulas for Illuminance, Luminous Flux and Luminous Intensity:
5
Name________________________
Physics
Chapter 16 – Light
Examples:
If a 3 way bulb can produce 665, 1620, 2285 lumens respectively, and 175 lux of
illumination is needed from a lamp 80 cm away, what is the minimum bulb
setting?
Find the illumination 4.0 m below a 405 lumen lamp. What is the luminous
intensity of the light?
A lamp has a Luminous flux (P) of 1000 lumens. What is the Illumination (E)
on a desk 3 m away? What is the Luminous Intensity [candle power] (I) of the
light?
6
Name________________________
Physics
Chapter 16 – Light
Light and Matter
A material that transmits light and allows objects to by seen clearly is a
______________________ material. (Examples: air, glass,
____________________)
A material that transmits light but does not permit objects to be seen clearly is
___________________________ material. (Examples: frosted glass,
____________________________)
A material that absorbs light or reflects light is an ________________________
material. (Examples: brick, _________________________________________)
By allowing white light to pass through a prism, a separation of color called
____________________________ occurs producing a visible _______________
(a rainbow effect).
Draw dispersion of white light:
7
Name________________________
Physics
Chapter 16 – Light
Colors and Pigments
When light of different colors combine ______________________________is
formed. This combination is called the
________________________________________________. The colors
combined are ________________________, __________________________,
and _____________________________. These colors are called the
_____________________________________. By adding primary colors in pairs
___________________________________ are formed.
Primary Colors
Secondary Colors
Draw a color wheel to show the additive process.
8
Name________________________
Physics
Chapter 16 – Light
Colors and Pigments
Objects appear a certain color because that color light (frequency) is reflected by
the object, or certain colors (frequencies) are absorbed.
Molecules that absorb certain wavelengths of light or reflect them are called
_____________________________.
Particles of colored material that absorb and reflect different wavelengths are
called ________________________.
The color of a dye or pigment that _______________________ one primary color
is a _____________________________________. A pigment that
_____________________ two primary colors is called a
____________________________________. The process is called the
________________________________________________.
Identify the primary pigments and what primary color they absorb:
9
Name________________________
Physics
Chapter 16 – Light
Colors and Pigments
Primary Pigments:
____________________________
____________________________
____________________________
Secondary Pigments
____________________________
____________________________
____________________________
Complimentary Pigments form _____________________________ (all color
absorbed. Colors formed by pigments (and dyes) are done by the
_______________________________________.
Identify the Primary and Secondary Pigment combination to produce Black.
________________________________________________________________
________________________________________________________________
________________________________________________________________
10
Name________________________
Physics
Chapter 16 – Light
Light Properties
Thin Film Properties
Color formation of a soap bubble or oil film on water is the result of constructive
and destructive ________________________________ of light waves as light
reflects from the outer and inner surface of the film. This is called
_____________________________________________________________.
When film is ___________________________________ thick for a particular
color of light (a specific frequency), that particular color of light is dispersed. A
rainbow pattern is produced on the film based on the thickness of the film.
Draw the interference pattern of thin film:
11
Name________________________
Physics
Chapter 16 – Light
Polarized Light
Considering the light wave using a transverse model, certain orientations of the
wave can be ____________________________ by certain material that prevents
the wave to pass through. This material is called a _________________________
material and the process of eliminating some or all of the light intensity (glare) is
called _______________________________________.
Draw a diagram of the effect of the polarized material on the light wave:
12
Name________________________
Chapter 16 - Review Questions
1. What is a ray and how is a ray used to study light? What aspect of the
electromagnetic wave does the ray model ignore?
2. Contrast luminous flux, luminous intensity, and illuminance.
3. What is the relationship between the illumination on a surface and the
distance the light source is from the surface?
4. Why does a tomato appear red in white light? Is this an additive or
subtractive process?
5. Compare a dye to a pigment (similarities and differences).
13
Name________________________
6. How can you tell whether light is polarized?
7. A red apple is illuminated by green light. What color would the apple
appear?
8. Jenny mixes magenta and green pigments. What color pigment does she
get?
9. A yellow lemon is illuminated by green light. What color does the lemon
appear?
10. A tie has blue spots on a yellow background. How does the ties appear
when illuminated by magenta light?
14