1) The document discusses different types of light sources including the sun, incandescent bulbs, fluorescent bulbs, and LED lights. 2) It describes how light waves interact with materials through transmission, absorption, reflection, scattering, and polarization. 3) The color of light and objects is determined by the wavelengths of light absorbed and reflected, with the primary colors for human vision being red, green, and blue.

1. Science Starter: March 5, 2012
Write out the definition and match the correct term
in your science notebook.
2) How a light wave bens when it enters a new
medium at an angle
3) How a light wave bounces back when it hits a
barrier
4) The type of wave visible light is
Electromagnetic Wave Refraction
Reflection Spectrum
Mechanical Wave Radiation

2. Science Starter: March 6, 2012
Write the question and correct answer in your science notebook
4) An EM wave is caused by a disturbance in
a. The atmosphere
b. A material medium
c. A field
5) In a vacuum, the speed of EM waves
a. Always remains constant
b. Decreases as the waves spread out
c. Depends on the source of the wave

3. Light Sources and Interactions

4. Facts about Visible Light
 Light is the only form of EM radiation for which
humans have specialized sensory organ.
 The human eye is very sensitive to light and color
 Most living creatures depend on visible light for their
survival.

5. Incandescence
 The Sun’s high temperature produces light of every
wavelength.
 Incandescence- the production of light by materials
at high temperatures
 Example: sun, lightening, fire, incandescent light bulbs

6. Living Things Produce Light
 Luminescence- the production of light without high
temperatures
 Bioluminescence- the production of light by living
organisms
 Light is created with a chemical process rather than intense
heat

7. Human Technology Produces Light
 Incandescent Light Bulbs- uses a glass bulb and a
tungsten filament
 Halogen Light Bulbs- used a quartz bulb, tungsten
filament, and a halogen gas mixture
 Fluorescent Light Bulbs- uses phosphor coating,
electrical current, mercury vapor and other gases.

8. Fluorescent and LED Lights
 Fluorescence- occurs when a material absorbs EM
radiation of one wavelength and gives off EM
radiation of another
 Light emitting diode (LED)- a semiconductor that
converts electric energy directly into light
 Advantages of LED: produce brighter light, do not break, uses
little energy and heat, can last for decades

9. Light Waves Interact with Materials
 Transmission- the passage of an EM wave through a
medium
 Transparent- materials that allow most of the light that strikes
to pass through
 Translucent- materials that transmit some light, but they also
cause it to spread out in all directions
 Opaque- materials that do not allow any light to pass through

10. Light Waves Interact with Materials
 Absorption- the disappearance of an EM wave into
the medium.
 Absorption affects how things look, because it limits the light
available to be reflected or transmitted.

11. Light Waves Interact with Materials
 Scattering- the spreading out of light rays in all
directions, because particles reflect and absorb the
light.

12. Light Waves Interact with Materials
 Polarization- quality of light in which all of its waves
vibrate in the same direction

13. Wavelengths Determine Color
 When all wavelengths of visible light are present the
light will appear white.
 A prism is a tool that uses refraction to spread out
the different wavelengths that make up white light.

14. Color Reflection and Absorption
 The color of an object or material is determine by the
wavelength it absorbs and reflects.

15. Primary Colors of Light
 The human eye detects three color bands: red, green
and blue.
 When all colors are mixed together you perceive
white light