1. It’s amazing!…Can you imagine life without it?
Light !!
It’s amazing!…Can you
imagine life without it?

2. Visible Spectrum
Visible spectrum (visible light): a combination of several different wavelengths of light traveling together. It is part of the Electromagnetic Spectrum.

3. Electromagnetic Spectrum
Electromagnetic waves are arranged by the degree of frequency, from radio waves to gamma waves.
They are waves that don’t require a medium (can travel through space)
E-waves all travel at the speed of light
The energy of the e-wave moves/ is transferred by radiation

4. Visible Spectrum

5. Visible Spectrum
Light is the electromagnetic wave that we can see with our eyes
ROYGBIV is the abbreviation for the color spectrum

6. How We See Light
Our eyes detect electromagnetic waves in the visible light range that allows us to see
Objects can be seen because they give off light
Their own light – luminous
Reflected light – illuminated

7. How We See Light…
Light reflecting off an object passes through the lens of the eye stimulates vision
The retina in the eye senses wavelengths of light as we perceive color
Light waves will either pass through, reflect or be absorbed by an object.

8. What We See…
The color that we see is determined by the wavelength reflected by the object
If all colors are absorbed – We see black
If all colors are reflected – We see white
What ever color is reflected – that’s the color we see.

9. Important to know… Compare and contrast reflection and refraction
Reflection Refraction

10. Vocabulary Reflection: the bouncing of light from a surface
Refraction: the bending of light as it passes through one material to another

11. Mirrors and Lenses Lenses refract - bend light rays as Mirrors reflect
they pass through
Mirrors reflect

12. Important to know…
Look at how light as it passes through a convex lens. How would you describe it?
A convex lens causes light to converge, or focus, producing an image that is smaller than the original object.

13. Essential Knowledge, Skills, and Processes
Look at what happens to light as it passes through a concave lens. How would you describe it?
A concave lens causes light to diverge, or spread out, producing a larger image than the original.

14. Mirrors: Plane, Concave & Convex
Plane Mirror Notes:
Has a flat surface
Image is right-side up
Image is the same size
Image is reversed left to right
A virtual image is formed
Use – bathroom mirrors, other mirrors in the home or in stores

15. Mirrors - Concave > than 1 focal length – upside down/real, reduced
Concave Mirror
Mirror curved inward
Image depends on optical axis, focal pt. focal length
Image depends on distance between object and mirror
> than 1 focal length – upside down/real, reduced
< than 1 focal length – right-side up, virtual, enlarged
Virtual and Real image
Use – Car headlights, flash lights

16. Mirrors - Convex Convex Mirror Mirror curved outward
reflected rays don’t cross in front
Extended behind mirror
Shows virtual images right-side up
Image is reduced (smaller)
Use – Security in stores, side car mirrors

17. Lenses - Concave Virtual image is reduced (smaller than the object)
Concave Lenses
Thinner in the middle
Light entering parallel to o. axis bend away from each other
Never forms a real image (always virtual)
Virtual image is reduced (smaller than the object)
Use: Telescopes, microscopes, eye glasses

18. Lenses - Convex Convex Lenses
If object is < 1 focal length form the lens, a virtual image is formed – and enlarged
If object is > than 2 focal lengths from lens, a real image is formed – and reduced (smaller)
Use: Magnifying lenses, Camera lens. Some eye glasses

19. Mirrors and Lenses Compared
Plane Mirror – V , same size/ reversed
Concave Mirror V & E Concave Lens V & R
R & R
Convex Mirror V & R Convex Lens V & E
V – Virtual
E – Enlarged
R – Reduced
R & R – Real and Reduced

20. Important to know… Eyeglasses: have lenses to make corrections
c. Hyperopia (farsightedness)
a. Normal eye
b. Myopia (nearsightedness)
Corrected with concave lens
Corrected with convex lens
No correction needed
If you are nearsighted, it’s hard to see
things that are far away.
If you are farsighted it’s difficult to view nearby objects

21. Important to know…
Explain the terms transparent, translucent, and opaque, and give an example of each.
Plastic wrap Wax paper Aluminum Foil
Transparent Translucent Opaque

22. Interaction of Light with Objects
Transmit or transmission: the passing of light through matter (air or objects).
Transparent: materials that allow all light to pass through – i.e., glass window, water
Translucent: letting light through but scattering it – i.e., wax paper
Opaque: materials that do not let light through - reflects - i.e., wood, metal

23. Mixing Colors of Light vs. Mixing Paints or Pigments
In order to get white light, must combine all colors of light
Red, blue and green are primary colors
When these combine they make secondary colors (cyan, magenta and yellow)
Mixing Colors of Pigments
Pigment is a material that gives a substance its color by absorbing some, reflecting others
Primary pigment colors: yellow, cyan, and magenta

24. Mixing Colors of Light vs. Mixing Paints or Pigments
Mixing Colors of Light Mixing Colors of Pigments